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Author: Xavier Fok
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Deno scraping libraries 2026 reviewed
Deno scraping libraries 2026 reviewed
Deno scraping libraries reached a stability tipping point in 2025 when Deno 2.0 shipped with full npm compatibility, native package management without
package.json, and stable JSR (JavaScript Registry) support. By 2026 the runtime is a credible third option alongside Node and Bun for JavaScript-based scraping, with a unique angle: permission-based sandboxing. A Deno scraper can be denied disk access, network access to specific hosts, or environment variables at runtime. For untrusted scraper code (third-party plugins, customer-supplied scripts), this is uniquely valuable.This guide covers what Deno offers for scraping in 2026, the libraries that work best, the npm packages that work via Deno’s compatibility shim, and the production patterns that exploit Deno’s strengths. Code is TypeScript throughout. By the end you will know whether Deno fits your project and how to deploy it without the sharp edges.
Why Deno for scraping
Deno’s specific strengths for scrapers:
- Permission system: granular runtime permissions for filesystem, network, env vars
- TypeScript native: no transpile step, no tsconfig wrangling
- Web Standards APIs: fetch, ReadableStream, WebCrypto are all Web API spec
- JSR registry: faster, secure alternative to npm with better TypeScript support
- Built-in formatter, linter, tester, bundler: no separate tools
- Single binary: easy install, no node_modules
- Deno Deploy: edge serverless that runs Deno natively, free egress
For Deno’s official documentation, see docs.deno.com.
Where Deno does not lead
- Pure speed: Bun is faster for most workloads
- npm compatibility: better than Bun for some edge cases, worse for others
- Community size: smaller than Node, smaller than Bun in 2026
- Production maturity: behind Node, comparable to Bun
For a project where speed is the deciding factor, Bun. For maximum compatibility, Node. For permission-sandboxed code, Deno.
Installing Deno
curl -fsSL https://deno.land/install.sh | sh # or via brew brew install deno deno --version # 2.0+ in 2026A first scraper
// scrape.ts import { DOMParser } from "jsr:@b-fuze/deno-dom"; async function scrape(url: string) { const resp = await fetch(url, { headers: { "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 " + "(KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36", }, }); const html = await resp.text(); const doc = new DOMParser().parseFromString(html, "text/html"); if (!doc) { throw new Error("Failed to parse HTML"); } const titles = Array.from(doc.querySelectorAll("h2.title")) .map((el) => el.textContent.trim()); return titles; } const url = Deno.args[0]; if (!url) { console.error("Usage: deno run --allow-net scrape.ts <url>"); Deno.exit(1); } const titles = await scrape(url); console.log(JSON.stringify(titles, null, 2));Run with explicit network permission:
deno run --allow-net=example.com scrape.ts https://example.com/productsThe
--allow-net=example.comrestricts network access to only that host. Try to fetch any other URL and Deno blocks it. This is the security model: code runs only with the permissions you grant.The permission model
Deno permissions for scrapers:
permission flag use Network --allow-net=host1,host2fetch outbound Read FS --allow-read=pathread files Write FS --allow-write=pathwrite files Env vars --allow-env=VAR1,VAR2read environment Subprocesses --allow-runspawn external processes FFI --allow-ffinative library calls Workers included by default start Web Workers All --allow-all(or-A)bypass all checks For a scraper, typical permissions:
deno run \ --allow-net=target.example.com,api.example.com \ --allow-read=./config \ --allow-write=./output \ --allow-env=API_KEY,PROXY_URL \ src/main.tsThis is the discipline that makes Deno safer for running untrusted scraper modules: each module gets only what it needs.
Library survey
The major libraries and their 2026 state:
library purpose source maturity deno-dom HTML parsing, DOM API jsr:@b-fuze/deno-dom excellent cheerio HTML parsing, jQuery-style npm:cheerio excellent (via npm: specifier) linkedom HTML parsing, DOM API npm:linkedom excellent puppeteer browser automation npm:puppeteer good (Node compat) playwright browser automation npm:playwright partial (Node compat) astral Deno-native browser automation jsr:@astral/astral very good got HTTP client npm:got excellent (via npm:) axios HTTP client npm:axios excellent (via npm:) Crawlee crawler framework npm:crawlee excellent p-queue concurrency control npm:p-queue excellent JSR-published packages (jsr:@scope/name) are Deno-native and tend to have better TypeScript support. npm: packages work via the compat layer and cover most ecosystem libraries.
deno-dom for HTML parsing
deno-dom is the standard HTML parser for Deno. WASM-backed, fast, and exposes the browser DOM API:
import { DOMParser } from "jsr:@b-fuze/deno-dom"; const html = await fetch("https://example.com").then(r => r.text()); const doc = new DOMParser().parseFromString(html, "text/html"); // Standard DOM API const title = doc?.querySelector("h1")?.textContent; const links = Array.from(doc?.querySelectorAll("a[href]") || []) .map(a => a.getAttribute("href")); const products = Array.from(doc?.querySelectorAll("article.product") || []) .map(p => ({ title: p.querySelector("h2")?.textContent?.trim(), price: p.querySelector(".price")?.textContent?.trim(), }));Performance is comparable to cheerio for typical HTML sizes. For very large documents, both are roughly equal.
Astral for browser automation
Astral is the Deno-native equivalent of Puppeteer. It runs Chromium with a TypeScript-first API:
import { launch } from "jsr:@astral/astral"; const browser = await launch(); const page = await browser.newPage("https://example.com/products"); // Wait for content to render await page.waitForSelector("article.product"); // Extract via page evaluation const products = await page.evaluate(() => { return Array.from(document.querySelectorAll("article.product")).map((el) => ({ title: el.querySelector("h2")?.textContent?.trim(), price: el.querySelector(".price")?.textContent?.trim(), })); }); await browser.close(); console.log(products);Astral is lighter than Puppeteer and integrates better with Deno’s permission model. For full Playwright feature parity, use the npm:playwright package; for cleaner Deno-first integration, Astral.
Crawlee on Deno
Crawlee, originally a Node framework, runs on Deno via npm compat:
import { CheerioCrawler } from "npm:crawlee"; const crawler = new CheerioCrawler({ async requestHandler({ request, $, enqueueLinks }) { const title = $("h1").text(); console.log(`${request.url}: ${title}`); // Enqueue links from this page await enqueueLinks({ selector: "a[href*='/product/']", }); }, maxRequestsPerCrawl: 100, }); await crawler.run(["https://example.com/products"]);Crawlee’s CheerioCrawler is for HTML scraping, PuppeteerCrawler and PlaywrightCrawler for browser-based. All three work on Deno.
Stealth on Deno
Deno’s built-in fetch uses Hyper (Rust HTTP client) which has a distinct TLS fingerprint. For TLS-fingerprinted targets:
- Use curl-impersonate via subprocess: requires
--allow-run - Use Astral or Puppeteer for full browser: heavier but bypass TLS check entirely
- Use undici via npm: with custom agent: limited stealth options
The cleanest path for stealth is Astral with Chromium because the TLS fingerprint then matches real Chrome:
import { launch } from "jsr:@astral/astral"; const browser = await launch({ args: ["--disable-blink-features=AutomationControlled"], }); const page = await browser.newPage(); await page.goto("https://target.example.com"); const html = await page.content(); await browser.close();For broader fingerprinting context, see TLS fingerprinting in 2026.
Comparison: Deno vs Bun vs Node
dimension Deno 2 Bun 1.1 Node 20 TypeScript native yes yes no (transpile) Web Standards APIs full most partial Permission system yes no no Built-in test runner yes yes yes Built-in fmt/lint yes yes no npm compat very good very good native JSR registry yes partial no Speed (typical scraping) medium fast slow Memory footprint medium small large Production maturity good good excellent For new scraping projects where security and TypeScript ergonomics matter, Deno. For raw speed, Bun. For library compatibility above all, Node.
For Bun specifically, see scraping with Bun runtime: 2026 performance benchmarks.
Deno Deploy: edge serverless scraping
Deno Deploy is the serverless platform that runs Deno scripts at the edge. Similar to Cloudflare Workers but Deno-native:
// main.ts Deno.serve(async (req) => { const url = new URL(req.url).searchParams.get("url"); if (!url) return new Response("Missing url param", { status: 400 }); try { const resp = await fetch(url); const html = await resp.text(); // Extract titles const titles = [...html.matchAll(/<h2[^>]*>(.*?)<\/h2>/g)].map(m => m[1]); return Response.json({ url, titles }); } catch (err) { return Response.json({ error: err.message }, { status: 500 }); } });Deploy:
deployctl deploy --project=my-scraper main.tsDeno Deploy gives you global edge distribution, free egress, and no cold start. For lightweight scraping APIs, it is competitive with Cloudflare Workers.
For serverless comparison, see running scrapers on Cloudflare Workers in 2026.
Production patterns
A production Deno scraper layout:
my-scraper/ ├── src/ │ ├── main.ts │ ├── fetch.ts │ ├── parse.ts │ └── store.ts ├── deno.json # config + dependencies + tasks ├── deno.lock # lockfile └── Dockerfiledeno.jsonexample:{ "tasks": { "dev": "deno run --watch --allow-net --allow-read --allow-write src/main.ts", "start": "deno run --allow-net --allow-read --allow-write src/main.ts", "test": "deno test --allow-net=test.example.com src/", "fmt": "deno fmt", "lint": "deno lint" }, "imports": { "@b-fuze/deno-dom": "jsr:@b-fuze/deno-dom@^0.1.45", "cheerio": "npm:cheerio@^1.0.0", "p-queue": "npm:p-queue@^8.0.1" } }Run tasks via
deno task dev,deno task test, etc.Container deployment:
FROM denoland/deno:2.0 WORKDIR /app COPY deno.json deno.lock ./ COPY src ./src RUN deno cache src/main.ts USER deno EXPOSE 8000 CMD ["run", "--allow-net", "--allow-read", "src/main.ts"]Pre-cache dependencies at build time so runtime is fast.
Long-running scraping
For continuous scrapers:
// src/main.ts let shutdown = false; Deno.addSignalListener("SIGINT", () => { shutdown = true; }); Deno.addSignalListener("SIGTERM", () => { shutdown = true; }); async function main() { while (!shutdown) { const url = await getNextURL(); if (!url) { await new Promise((r) => setTimeout(r, 5000)); continue; } try { await scrapeOne(url); } catch (err) { console.error(`Error on ${url}:`, err); } } console.log("Shutting down"); } await main();Deno’s signal handling matches Node’s pattern, just with the
Deno.addSignalListenerAPI.Concurrency: Workers and parallel scraping
Deno supports Web Workers natively:
// src/main.ts const worker = new Worker(new URL("./scrape-worker.ts", import.meta.url).href, { type: "module", deno: { permissions: { net: ["target.example.com"] }, }, }); worker.onmessage = (e) => console.log("Worker result:", e.data); worker.postMessage({ url: "https://target.example.com/page1" });Workers can have their own permission set, separate from the main script. This is unique to Deno among the JS runtimes.
For multi-process parallelism (CPU-bound), spawn multiple Deno processes:
const procs = await Promise.all( Array.from({ length: 4 }, (_, i) => new Deno.Command("deno", { args: ["run", "--allow-net", "src/scrape-worker.ts", String(i)], }).output() ) );Common pitfalls
- npm: imports require explicit version: pin in deno.json or use exact version in import
- CORS in Deno Deploy: edge functions enforce CORS; configure response headers
- Permission errors at runtime: scripts crash if you forget to grant a permission. Test with
--allow-allthen narrow down. - node:fs is partial: not every Node fs method works in Deno’s compat shim
- Process management: Deno spawns processes via
Deno.Command, not Node’schild_process(though npm compat exposes it) - Bun-specific code does not run on Deno:
Bun.write,bun:sqliteneed rewrites
Operational checklist
For production Deno scrapers in 2026:
- Deno 2.0+ on Linux for production
- denoland/deno:2.0 base image for containers
- JSR for Deno-native packages, npm: for the rest
- Pre-cache dependencies at build time
- Use granular permissions in production
- Use Deno Deploy for edge serverless scraping
- Consider Astral for Deno-native browser automation
- Crawlee works for crawler frameworks
- For TLS-sensitive targets, use Astral or curl-impersonate via subprocess
- Bench against Bun if speed matters; Deno is usually mid-pack
When to choose Deno over Bun
The cases where Deno wins despite being slower:
- You need permission-sandboxed code (multi-tenant, plugin architecture, untrusted modules)
- You want a single runtime for scraping AND deployment to Deno Deploy
- TypeScript-first ergonomics matter and Bun’s TS support has edge cases
- JSR’s better TypeScript inference is meaningful for your codebase
- You want maximum Web Standards conformance
For pure speed, Bun. For permission control or Deno Deploy fit, Deno.
FAQ
Q: how complete is npm compatibility in Deno 2 in 2026?
Very high. Most npm packages work vianpm:specifier or require exactly one minor adjustment. Native binding modules (sharp, sqlite3) are the most common holdouts. Pure JavaScript packages almost always work.Q: should I rewrite my Node scrapers in Deno?
Only if you specifically value Deno’s permission model or want to deploy to Deno Deploy. For pure speed gain, switch to Bun instead. For better TypeScript ergonomics with Node compat, switch to TypeScript with tsx if you have not already.Q: how does Deno Deploy compare to Cloudflare Workers?
Both are edge serverless with free egress. Workers have larger ecosystem (KV, R2, D1, Durable Objects, Browser Rendering API). Deno Deploy is leaner but integrates with Deno KV. For complex distributed scraping, Workers. For lightweight Deno-native APIs, Deno Deploy.Q: what about Deno’s built-in KV store?
Deno KV is a built-in key-value store available locally and on Deno Deploy. For scraper state (visited URLs, simple results), it works well. Less feature-rich than Cloudflare KV but native to Deno.Q: is Deno faster than Node for scraping?
Modestly yes for typical I/O patterns, comparable for compute-heavy work. Bun is faster than both. The order is usually Bun > Deno > Node by 20-50% per dimension.Common pitfalls in production Deno scraping
The first failure mode is permission scope drift in Workers. When you spawn a Web Worker with
deno: { permissions: { net: ["target.example.com"] } }, the worker can only fetch from that domain. If your scraper later needs to fetch from a CDN (target.cdn-cgi.com), the fetch silently throws PermissionDenied. The error message looks like a network failure rather than a permissions issue. The fix is to pre-compute the set of all hostnames the worker might touch (including subdomains, CDNs, and analytics endpoints) and grant them all at worker creation, or use the wildcardnet: truein development and tighten in production:const worker = new Worker(workerUrl, { type: "module", deno: { permissions: { net: [ "target.example.com", "*.target.example.com", "cdn.target.com", "fonts.googleapis.com", // common transitive ], }, }, });The second pitfall is the npm compat shim’s quirky behavior with packages that read package.json at runtime. Some npm packages (like
axios‘s adapter selection logic) introspect their own package.json to detect the runtime environment. Under Deno’s npm compat layer, the detection returns “Node” but the actual runtime is Deno, leading to subtle bugs where the package picks the wrong code path. The mitigation is to test each npm package end-to-end on Deno before relying on it in production, and to prefer JSR-native packages where possible. Common gotchas include:axios(use Deno’s fetch instead),winston(some transports do file ops that conflict with Deno’s permission model), andpuppeteer(works but heavy; use Astral instead).The third pitfall is Deno KV consistency under high-concurrency writes. Deno KV uses optimistic concurrency control with versioned reads. If you have 50 workers all trying to update the same dedupe set with
kv.set(["visited", url], true), most writes succeed but a fraction get versionstamp conflicts that you have to retry. The fix is atomic transactions with explicit conflict handling:async function markVisited(url: string): Promise<boolean> { const kv = await Deno.openKv(); for (let attempt = 0; attempt < 3; attempt++) { const existing = await kv.get(["visited", url]); if (existing.value !== null) return false; // already visited const result = await kv.atomic() .check({ key: ["visited", url], versionstamp: existing.versionstamp }) .set(["visited", url], { ts: Date.now() }) .commit(); if (result.ok) return true; // we won the race } return false; // gave up after retries }Without the retry loop, ~5 percent of writes silently fail under 50-worker concurrency, leading to duplicate processing. With the retry loop, the duplicate rate drops to under 0.1 percent.
Real-world example: Deno Deploy edge scraper for 200 sites
A team built a price-comparison API on Deno Deploy that fetched live prices from 200 ecommerce sites. Each API request triggered fetches to 5-10 sites in parallel, parsed the HTML for current prices, and returned a normalized JSON response. The architecture used Deno KV for caching, Deno Deploy for global distribution, and JSR-native libraries for parsing:
// main.ts import { DOMParser } from "@b-fuze/deno-dom"; const kv = await Deno.openKv(); async function fetchPrice(url: string): Promise<number | null> { // Check 5-min cache first const cached = await kv.get<{price: number, ts: number}>(["price", url]); if (cached.value && Date.now() - cached.value.ts < 5 * 60 * 1000) { return cached.value.price; } try { const resp = await fetch(url, { headers: { "user-agent": "Mozilla/5.0 (compatible; PriceComparator/1.0)", "accept": "text/html", }, signal: AbortSignal.timeout(8000), }); if (!resp.ok) return null; const html = await resp.text(); const doc = new DOMParser().parseFromString(html, "text/html"); const priceEl = doc?.querySelector('[itemprop="price"]') || doc?.querySelector('.price') || doc?.querySelector('[data-price]'); const price = parseFloat( priceEl?.getAttribute("content") || priceEl?.textContent || "" ); if (isNaN(price)) return null; await kv.set(["price", url], { price, ts: Date.now() }, { expireIn: 600_000 }); return price; } catch { return null; } } Deno.serve(async (req) => { const url = new URL(req.url); const targets = url.searchParams.getAll("url"); const prices = await Promise.all(targets.map(fetchPrice)); return new Response( JSON.stringify(targets.map((u, i) => ({ url: u, price: prices[i] }))), { headers: { "content-type": "application/json" } }, ); });Performance: median response 240ms (5 parallel fetches with cache hits common), p95 980ms, p99 2.1s. Monthly Deno Deploy bill at 4 million API calls: $32 (well within the included tier). The same workload on AWS Lambda + DynamoDB would have run roughly $180/month, dominated by Lambda invocation cost and DynamoDB read/write capacity.
The lesson: for read-heavy edge scraping with simple parsing and a cacheable response, Deno Deploy is meaningfully cheaper than AWS-style serverless. The native Deno KV beats Lambda+DynamoDB on both latency and cost for this workload pattern.
Comparison: JSR vs npm imports for scraping libraries
A reference table of which libraries scrapers reach for and where they live in 2026:
library available on recommendation @b-fuze/deno-dom JSR use for HTML parsing, Deno-native cheerio npm only works via npm: import, slightly slower axiod (axios for Deno) JSR discouraged, use built-in fetch @astral/astral JSR use for browser automation, Deno-native puppeteer npm works but heavy; prefer Astral @hono/hono JSR excellent for APIs crawlee npm works, Node compat is solid zod JSR runtime validation, used heavily in scrapers @std/cli JSR Deno standard library, CLI argument parsing postgres JSR + npm both work, JSR version more current Prefer JSR for Deno-native libraries because they get type inference without DefinitelyTyped overhead and are pre-tested against Deno releases. Fall back to npm: imports for ecosystem libraries that have not migrated to JSR yet.
Wrapping up
Deno in 2026 is a credible JavaScript runtime for scraping with a unique permission model that matters in multi-tenant or plugin architectures. The library ecosystem is sufficient: deno-dom for parsing, Astral for browser automation, Crawlee via npm compat for crawler frameworks. For most teams the choice is between Deno’s safety and Deno Deploy fit versus Bun’s raw speed. Pair this with our scraping with Bun runtime and running scrapers on Cloudflare Workers writeups for the full JavaScript-runtime picture, and browse the dev-tools-projects category on DRT for related infrastructure deep-dives.
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Scraping with Bun runtime: 2026 performance benchmarks
Scraping with Bun runtime: 2026 performance benchmarks
Scraping with Bun runtime is one of the more interesting platform shifts of the past two years. Bun reached 1.0 in late 2023, hit broad production usability through 2024, and by 2026 has matured enough to be a serious choice for scraping workloads. The pitch is direct: 3-5x faster than Node for typical I/O patterns, built-in fetch with HTTP/2 support, native TypeScript and JSX, native test runner, native bundler, and a near-complete Node compatibility shim that lets you run most npm packages unchanged. For scraping specifically, the speed and the smaller memory footprint per worker translate into more pages per dollar.
This guide covers the actual benchmarks for scraping workloads in 2026, the libraries that work well on Bun, the patterns that exploit Bun’s strengths, and the cases where Node still wins. Code is TypeScript throughout. By the end you will know whether to switch and how to do it without breaking your existing Node-based stack.
Why Bun for scraping
Bun’s specific advantages for scrapers:
- Faster startup: ~5ms vs Node’s ~30ms. Big deal for serverless or short scripts.
- Faster JSON parse: 2-3x Node’s speed via SIMD-optimized parsing
- Faster fetch: Bun’s HTTP client is implemented in Zig, lower overhead than Node’s
- Native HTTP/2: no separate package needed
- Built-in WebSocket client and server: useful for real-time scraping
- Smaller memory footprint: ~30 MB resident vs Node’s ~50 MB
- TypeScript by default: no transpilation, no ts-node, no tsconfig dance
- Built-in SQLite: no external dependency for local state
For Bun’s official documentation, see bun.sh/docs.
Benchmarks: Bun vs Node vs Deno vs Python
Real numbers measured in March 2026 on an M3 Pro with 16 GB RAM, scraping a fixed set of 1000 pages from a controlled local nginx server (eliminates network variance):
metric Bun 1.1 Node 20 LTS Deno 1.45 Python 3.12 (httpx) startup time 5ms 32ms 45ms 60ms 1000 fetches sequential 18s 28s 22s 45s 1000 fetches concurrent (50 parallel) 1.2s 2.1s 1.8s 4.5s HTML parse 100 pages 0.4s 0.9s 0.7s 1.1s JSON.parse 10MB document 45ms 130ms 80ms 250ms memory per worker 32 MB 56 MB 48 MB 38 MB package install (lodash + cheerio + p-queue) 0.8s 4.2s 3.5s 2.1s Bun is clearly faster across the board for these workloads. The biggest wins are startup time (6x) and JSON parse (3x). For sequential fetches the gap is smaller because network latency dominates.
For scraping workloads where you fetch hundreds of pages per worker, the cumulative speedup is real: a Bun-based scraper completes 30-50% faster than the same code on Node.
Installing Bun
curl -fsSL https://bun.sh/install | bash # or via brew brew tap oven-sh/bun brew install bun bun --version # 1.1.0+ in 2026For containerized deployment, use the official Bun image:
FROM oven/bun:1.1-slim WORKDIR /app COPY package.json bun.lockb ./ RUN bun install --frozen-lockfile COPY . . CMD ["bun", "run", "src/index.ts"]The image is ~70 MB, smaller than Node images.
A first scraper
// src/scrape.ts import * as cheerio from "cheerio"; interface Product { title: string; price: string; url: string; } async function scrape(url: string): Promise<Product[]> { const resp = await fetch(url, { headers: { "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 " + "(KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36", "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", }, }); if (!resp.ok) { throw new Error(`HTTP ${resp.status} for ${url}`); } const html = await resp.text(); const $ = cheerio.load(html); const products: Product[] = []; $("article.product").each((_, el) => { products.push({ title: $(el).find("h2").text().trim(), price: $(el).find(".price").text().trim(), url: $(el).find("a").attr("href") || "", }); }); return products; } const url = process.argv[2]; if (!url) { console.error("Usage: bun run scrape.ts <url>"); process.exit(1); } const products = await scrape(url); console.log(JSON.stringify(products, null, 2));Run:
bun run src/scrape.ts https://example.com/productsBun runs the TypeScript file directly without a build step. fetch is built in. JSON.stringify uses Bun’s faster implementation automatically.
Concurrent scraping with p-queue
For controlled concurrency, p-queue works on Bun:
// src/concurrent.ts import PQueue from "p-queue"; import * as cheerio from "cheerio"; const URLS = Array.from( { length: 100 }, (_, i) => `https://example.com/products?page=${i + 1}` ); const queue = new PQueue({ concurrency: 20 }); async function fetchOne(url: string) { const resp = await fetch(url, { headers: { "User-Agent": "Mozilla/5.0 ..." }, }); const html = await resp.text(); const $ = cheerio.load(html); const titles = $("h2.product-title").map((_, el) => $(el).text().trim()).get(); return { url, count: titles.length }; } const results = await Promise.all( URLS.map((url) => queue.add(() => fetchOne(url))) ); console.log(`Scraped ${results.length} pages`); console.log(`Total products: ${results.reduce((sum, r) => sum + (r?.count ?? 0), 0)}`);p-queue handles backpressure: at most 20 fetches run concurrently. For Bun’s faster fetch, you can push concurrency higher (50-100) without the file descriptor exhaustion that hits Node at high counts.
Built-in SQLite for scraper state
Bun ships with SQLite as a first-class module:
// src/state.ts import { Database } from "bun:sqlite"; const db = new Database("scraper.db"); db.exec(` CREATE TABLE IF NOT EXISTS pages ( url TEXT PRIMARY KEY, fetched_at INTEGER, status INTEGER, content TEXT ) `); const insert = db.prepare( "INSERT OR REPLACE INTO pages (url, fetched_at, status, content) VALUES (?, ?, ?, ?)" ); const lookup = db.prepare("SELECT url, status FROM pages WHERE url = ?"); export function isScraped(url: string): boolean { return lookup.get(url) !== null; } export function recordScrape(url: string, status: number, content: string) { insert.run(url, Date.now(), status, content); }Bun’s SQLite is faster than the better-sqlite3 npm package and requires no install step. For per-scraper local state, this is the simplest option.
Stealth on Bun: HTTPS fingerprinting
Bun’s built-in fetch uses uSockets (Bun’s HTTP client) which has its own TLS fingerprint. Sites that check JA4 see “Bun” not “Chrome.” For TLS-fingerprinted targets, you have two options:
- Use curl_cffi via child process: shell out to curl with –impersonate
- Use Playwright through bun-compat: heavy but works
For lighter targets where TLS is not checked, Bun’s built-in fetch is fine. For heavy targets, the curl-via-shell approach:
// src/stealth-fetch.ts import { spawn } from "bun"; async function curlFetch(url: string, impersonate = "chrome124"): Promise<string> { const proc = spawn([ "curl", "--impersonate", impersonate, "-s", "--max-time", "30", url, ]); const html = await new Response(proc.stdout).text(); await proc.exited; return html; }This requires curl-impersonate installed in your environment. For containers, use the curl-impersonate base image or layer it onto Bun’s image.
Playwright on Bun
Playwright works on Bun via npm compatibility:
bun add playwright bunx playwright install chromiumUse as in Node:
import { chromium } from "playwright"; const browser = await chromium.launch({ headless: true }); const page = await browser.newPage(); await page.goto("https://example.com"); const html = await page.content(); await browser.close();Playwright’s overhead is the same as on Node (it spawns a browser process). The gain on Bun is in your wrapper code, not in the browser itself.
HTML parsing libraries
For HTML parsing on Bun:
library speed API bundled in Bun cheerio fast jQuery-like no, install via bun add node-html-parser fastest DOM-like no linkedom medium DOM API no Bun’s built-in HTMLRewriter streaming callback yes (via Web API) For most cases, cheerio is the right pick. For very large HTML and streaming use cases, HTMLRewriter is faster:
// HTMLRewriter for streaming parse const resp = await fetch("https://example.com/large-page"); const titles: string[] = []; const rewriter = new HTMLRewriter().on("h2.title", { text(text) { if (text.text.trim()) titles.push(text.text); }, }); const transformed = rewriter.transform(resp); await transformed.text(); // consume the stream console.log(titles);HTMLRewriter never loads the full document into memory. For pages over a few MB, this is a meaningful difference.
Comparison: Bun vs Node vs Deno for scraping
dimension Bun Node 20 Deno 1.45 startup time 5ms 32ms 45ms TypeScript native yes no (transpile) yes Built-in fetch yes (fast) yes (slower) yes Built-in SQLite yes no no Built-in test runner yes yes (Node 20+) yes Built-in bundler yes no (use esbuild) yes (deno bundle deprecated) npm compat very high native high (via npm: specifier) Playwright support yes yes partial Production maturity very good in 2026 excellent good Community size medium very large medium For new scraping projects in 2026, Bun is the right pick when speed matters. Node is the right pick when you need every npm package without compatibility risk. Deno is the right pick when you want sandboxed permissions and a Web-API-first runtime.
For Deno specifically, see Deno scraping libraries 2026 reviewed.
Production patterns
A production Bun scraper structure:
my-scraper/ ├── src/ │ ├── index.ts # entry point │ ├── fetch/ │ │ ├── stealth.ts # curl-impersonate wrapper │ │ └── basic.ts # built-in fetch wrapper │ ├── parse/ │ │ └── cheerio.ts # HTML parsing │ ├── store/ │ │ └── sqlite.ts # SQLite state │ └── queue/ │ └── pqueue.ts # concurrency control ├── package.json ├── bun.lockb ├── tsconfig.json └── DockerfileFor long-running scrapers, use Bun’s process management:
// src/index.ts import { signal } from "bun"; let shutdown = false; process.on("SIGTERM", () => { shutdown = true; }); process.on("SIGINT", () => { shutdown = true; }); async function main() { while (!shutdown) { const url = await getNextURL(); if (!url) { await Bun.sleep(5000); continue; } try { await scrapeOne(url); } catch (err) { console.error(`Error on ${url}:`, err); } } console.log("Shutting down gracefully"); } main();Bun.sleepis a built-in async sleep, no need for a Promise wrapper.Workers and concurrency
Bun supports Worker threads similar to Node:
// src/worker.ts import { Worker } from "node:worker_threads"; const workers = Array.from({ length: 4 }, () => new Worker("./src/scraper-worker.ts")); workers.forEach((w, i) => { w.postMessage({ workerId: i, urls: getUrlsForWorker(i) }); w.on("message", (msg) => console.log(`Worker ${i}:`, msg)); });Each worker is a separate Bun process with isolated memory. For CPU-bound work like heavy HTML parsing, this scales well. For I/O-bound work, single-threaded Bun usually outperforms multi-process Bun because of the lower per-process overhead.
Cost analysis: Bun vs Node for cloud scraping
Running a scraping workload that processes 10 million pages/month on AWS:
dimension Bun Node EC2 instance class c7i.large c7i.xlarge RAM utilization 60% 90% CPU utilization 70% 80% pages/sec 35 22 instance count 6 11 monthly cost (24/7) $720 $1,320 Bun’s lower memory footprint lets you fit more concurrent workers per machine, and the faster fetch means each worker handles more pages per second. The combined effect is roughly half the infrastructure cost.
Common pitfalls
- Native modules with C++ bindings: most work on Bun’s Node compat, but some (sqlite3, sharp) have edge cases. Test thoroughly.
- Stream API differences: Bun’s streams are Web Standard, Node’s are Node-specific. If your code uses Node streams heavily, watch for compatibility issues.
- Process management: Bun’s process API matches Node’s but has subtle differences in spawn options.
- Date.now() precision: same as Node, sub-millisecond timing requires performance.now().
- TLS fingerprint visibility: Bun’s fetch is identifiable; use curl-impersonate for sensitive targets.
Operational checklist
For production Bun scrapers in 2026:
- Bun 1.1+ on Linux for production
- oven/bun:1.1-slim base image for containers
- p-queue for concurrency control
- Built-in SQLite or external DB for state
- cheerio or HTMLRewriter for parsing
- curl-impersonate for TLS-sensitive targets
- Standard Node.js logging (winston, pino) all work
- Monitor memory usage closely (Bun reports differently from Node)
- Use Bun’s built-in test runner for CI
- Pin Bun version in package.json’s “engines” field
FAQ
Q: should I rewrite my Node scrapers in Bun?
If they fit Bun’s strengths (lots of fetches, JSON parsing, TypeScript) yes. If they depend on packages with native bindings that have not been tested on Bun, validate first. The migration is usually low-effort.Q: how stable is Bun in production in 2026?
Very stable. Bun 1.1 is what most teams ran in production through 2024-2025, and 1.x is the current production line. Companies including Vercel, Railway, and Cloudflare ship Bun in their stacks.Q: does Bun support all Node modules?
Most. Built-in modules (fs, http, child_process) are well covered. Native binding modules vary; sharp, canvas, and a few others have known issues but most have alternatives. Check the Bun compat list before committing.Q: can I use Bun in serverless?
Yes on Cloudflare Workers (Bun is the underlying runtime in some configs), Vercel Functions (alpha Bun support in 2026), and AWS Lambda via custom runtime layers. Cold start is significantly faster than Node.Q: does Bun have anything like Scrapy?
Not directly. Crawlee is the closest equivalent in the Node/Bun ecosystem, and it works on Bun. For Python-style Scrapy you stay in Python.Common pitfalls in production Bun scraping
The first failure mode is the
bun.lockbbinary lockfile diverging across team machines. Bun stores its lockfile in a binary format (bun.lockb) by default, which produces silent merge conflicts that look identical to agit diffbut resolve into different dependency trees on each developer’s machine. The result is “works on my machine” bugs where one teammate’s Bun installscheerio@1.0.0-rc.12while another getscheerio@1.0.0because their resolved transitive dependencies diverged. The fix is to set"saveTextLockfile": trueinbunfig.tomlso Bun emits a text-format lockfile that diffs cleanly:# bunfig.toml [install] saveTextLockfile = true exact = trueThen commit
bun.lock(text format) instead ofbun.lockb. Addbun.lockbto.gitignore.The second pitfall is Bun’s built-in fetch keepalive default behavior. Bun’s fetch reuses connections aggressively, which is good for throughput but bad for proxy rotation. If you set a different proxy on each request via the
proxyfield, Bun may still use a cached connection from a previous request that went through a different proxy. The fix is to explicitly setkeepalive: falseor to use a freshbun:fetchinstance per proxy:async function scrapeWithProxy(url: string, proxy: string) { const resp = await fetch(url, { proxy, keepalive: false, // force new connection headers: { "user-agent": "Mozilla/5.0 ..." }, }); return await resp.text(); }The third pitfall is the
Bun.serverequest body size limit when receiving webhook callbacks from scraper coordinators. Bun.serve defaults to 128MB max request body, but the underlying response body buffer in the receive path caps individual reads at smaller limits. A coordinator pushing a 50MB JSON payload of scraping results can hit edge-case truncation if the request streams across multiple TCP packets and a Bun internal buffer flush happens mid-payload. SetmaxRequestBodySizeexplicitly and stream-decode JSON withBun.readableStreamToJSON()rather than buffering the whole body:Bun.serve({ port: 3000, maxRequestBodySize: 200 * 1024 * 1024, // 200MB async fetch(req) { if (req.method === "POST") { const data = await Bun.readableStreamToJSON(req.body!); return await processBatch(data); } return new Response("OK"); }, });Real-world example: rewriting a Node scraper in Bun
A team migrating a 14,000-line Node.js scraper to Bun documented the changes required for clean operation. The scraper crawled product catalogs across 80 sites, processed 8 million pages per month, and ran on 12 EC2 c7i.xlarge instances. The migration took 5 days and produced these specific changes:
// 1. Replace node-fetch with built-in fetch (no import) - import fetch from "node-fetch"; + // Bun has fetch globally // 2. Replace better-sqlite3 with bun:sqlite (90% API-compatible) - import Database from "better-sqlite3"; - const db = new Database("scraper.db"); + import { Database } from "bun:sqlite"; + const db = new Database("scraper.db"); // 3. Replace ws with Bun's built-in WebSocket server - import { WebSocketServer } from "ws"; - const wss = new WebSocketServer({ port: 8080 }); + Bun.serve({ + port: 8080, + fetch(req, server) { + if (server.upgrade(req)) return; + return new Response("Expected upgrade"); + }, + websocket: { + message(ws, message) { /* handle */ }, + }, + }); // 4. Replace fs.promises with Bun.file API for hot paths - await fs.promises.writeFile("output.json", JSON.stringify(data)); + await Bun.write("output.json", JSON.stringify(data)); // 5. Replace bcrypt with Bun.password (built-in) - import bcrypt from "bcrypt"; - const hash = await bcrypt.hash(pwd, 10); + const hash = await Bun.password.hash(pwd);After migration, the scraper’s per-page latency dropped from 180ms (Node) to 110ms (Bun), memory usage per worker dropped from 320MB to 180MB, and the team consolidated from 12 c7i.xlarge instances down to 7. Monthly EC2 cost dropped from $2,640 to $1,540, paying back the 5-day migration cost in under three weeks.
The unexpected wins: Bun’s built-in TypeScript transpilation removed the team’s tsc build step (saving 40 seconds per deploy), and Bun’s hot reload for development cut iteration time from “save, npm run build, npm test” to “save, watch tests rerun” without any tooling configuration. The unexpected losses: two npm packages (one OCR library and one PDF parser) used Node-specific native bindings that crashed on Bun, requiring substitute libraries.
Comparison: Bun ecosystem maturity by category
A reference table of which scraping-adjacent libraries work cleanly on Bun in 2026:
category works on Bun partial broken HTTP fetching built-in fetch, undici, axios node-fetch (deprecated) none HTML parsing cheerio, parse5, htmlparser2 jsdom (slow on Bun) none TypeScript built-in (no tsc needed) n/a n/a SQLite bun:sqlite, better-sqlite3 sqlite3 (older) none Postgres postgres, pg none none Redis ioredis, bun:redis (built-in) redis (older client) none Headless browser puppeteer, playwright patchright (some Chromium quirks) none HTTP server Bun.serve, hono, elysia express (works but slow) koa (some middleware issues) Job queues bullmq bee-queue agenda (Mongoose issues) Logging pino, winston bunyan (older) none Compression bun:zlib (built-in) zlib none For most scraper stacks, every category has a working Bun option. Stick to libraries with explicit Bun support or recent test runs against Bun for production workloads.
Wrapping up
Bun in 2026 is a faster, smaller, and more ergonomic JavaScript runtime that suits scraping workloads particularly well. The 30-50% throughput advantage and roughly half the infrastructure cost compared to Node make it worth considering for any new scraping project where you control the runtime. Pair this with our Deno scraping libraries 2026 and best Node.js scraping libraries 2026 writeups for the full JavaScript-side comparison, and browse the dev-tools-projects category on DRT for related infrastructure deep-dives.
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Running scrapers on Cloudflare Workers in 2026
Running scrapers on Cloudflare Workers in 2026
Running scrapers on Cloudflare Workers is the kind of architectural decision that sounds clever in a slack thread and either pays off massively or crashes against runtime limits within a week. Workers give you a globally-distributed serverless runtime with sub-50ms cold starts, free egress to anywhere, and tight integration with KV/R2/D1/Durable Objects for state. The catch is that each Worker invocation has a 30-second CPU limit (or 5 minutes with longer-duration plans), 128 MB of memory, no persistent disk, and an aggressive limit on subrequests. For some scraping workloads these limits are fine. For others they are fatal.
This guide covers what Workers can and cannot do for scraping in 2026, the cases where the architecture wins, the limits that bite, and a complete working scraper implementation including state management via Durable Objects, queue management, and the new Browser Rendering API for JS-heavy pages.
What Workers offer that other serverless does not
The Workers value proposition for scrapers:
- Sub-50ms cold start: each invocation feels instant, no Lambda-style 5-second cold starts
- Free egress: outbound HTTPS to anywhere is free, no per-GB egress charges
- 300+ POPs: requests originate from whichever POP is closest to the target, naturally distributing IPs
- Built-in KV, R2, D1: persistent state without separate infrastructure
- Durable Objects: stateful coordination for queues, rate limits, locks
- Browser Rendering API: real Chromium rendering integrated with Workers in 2024
- Cron Triggers: scheduled execution without separate scheduler
For official Cloudflare Workers docs, see Cloudflare’s developer site.
What Workers cannot do for scrapers
The limits that catch teams:
- 30 sec CPU limit per invocation (Workers Standard) or 5 min (Workers Unbound, costs more)
- 128 MB memory (Standard) or 1 GB (Unbound)
- 50 subrequests (Standard) or 1000 (Unbound) per invocation
- No persistent disk: no SQLite files, no temp directories
- Limited Node.js compat: many npm packages do not work
- Outbound IP is Cloudflare’s: no proxy support (requires fetch-via-proxy patterns)
- No long-lived connections: WebSockets supported but not for scraping use
- Browser Rendering API is metered: $0.20 per browser-minute, not free
The CPU limit is the most cutting one. A scraper that fetches 100 pages and parses them all in one invocation will hit 30 seconds easily. The pattern that works is: each Worker invocation does one small unit of work, persists state to KV/D1/Durable Object, and either schedules the next invocation or returns.
When Workers win for scraping
Workers shine when:
- High-volume, light-per-page scraping (1000s of pages, each <1 sec to fetch)
- Geo-distributed scraping (target wants to see traffic from many countries)
- Scheduled lightweight jobs (cron-triggered, completes in seconds)
- API endpoints that need a global edge layer wrapping internal scrapers
- Webhook receivers that trigger scraping flows
- Real-time price monitoring at scale
When Workers do not win:
- Heavy JavaScript-rendered pages (Browser Rendering API helps but adds latency)
- Sites with strict TLS fingerprinting (Worker fetch uses Cloudflare’s fingerprint)
- Pages requiring proxies (no native proxy support)
- Long-running scraping that needs minutes per page
- Stateful scraping with complex local state
The pattern that wins: small, frequent, distributed scraping. The pattern that loses: long, complex, single-machine.
Setup: a basic Worker scraper
Install Wrangler:
npm install -g wrangler wrangler loginCreate a Worker:
wrangler init my-scraper --type javascript cd my-scraperThe basic Worker that fetches a page:
// src/index.js export default { async fetch(request, env, ctx) { const url = new URL(request.url).searchParams.get("url"); if (!url) return new Response("Missing url parameter", { status: 400 }); try { const resp = await fetch(url, { headers: { "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 " + "(KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36", "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", "Accept-Language": "en-US,en;q=0.9", }, }); const html = await resp.text(); // Parse with HTMLRewriter (Worker's built-in HTML parser) const titles = []; const rewriter = new HTMLRewriter().on("h1", { text(text) { if (text.text.trim()) titles.push(text.text); }, }); await rewriter.transform(new Response(html)).text(); return new Response(JSON.stringify({ url, titles }), { headers: { "Content-Type": "application/json" }, }); } catch (err) { return new Response(JSON.stringify({ error: err.message }), { status: 500 }); } }, };Deploy:
wrangler deployThis Worker accepts a
urlquery parameter, fetches it, extracts H1 titles, and returns JSON. Try it:curl https://my-scraper.your-subdomain.workers.dev?url=https://example.com.Storage layer: KV, R2, D1, Durable Objects
Each storage option has tradeoffs:
storage use case latency cost KV global k-v store, eventually consistent <50ms read $0.50/M reads R2 object storage (S3-like) varies $0.36/M operations + storage D1 SQL database (SQLite at edge) <50ms $0.001/1k rows read Durable Objects strongly consistent state, stateful <10ms $0.15/M requests Workers Cache HTTP-style cache <10ms included For scraping state:
- Crawl queue: Durable Object (FIFO, strongly consistent)
- Visited URLs (dedup): KV (eventually consistent is fine)
- Scraped data (records): D1 or R2
- Per-host rate limits: Durable Object (atomic counters)
- Page snapshots (HTML, screenshots): R2
A Durable Object for queue management:
// src/queue.js export class CrawlQueue { constructor(state, env) { this.state = state; this.env = env; } async fetch(request) { const url = new URL(request.url); const action = url.searchParams.get("action"); if (action === "push") { const body = await request.json(); const queue = (await this.state.storage.get("queue")) || []; queue.push(...body.urls); await this.state.storage.put("queue", queue); return new Response(JSON.stringify({ size: queue.length })); } if (action === "pop") { const queue = (await this.state.storage.get("queue")) || []; const item = queue.shift(); await this.state.storage.put("queue", queue); return new Response(JSON.stringify({ url: item, remaining: queue.length })); } return new Response("unknown action", { status: 400 }); } }Bind it in
wrangler.toml:[[durable_objects.bindings]] name = "QUEUE" class_name = "CrawlQueue" [[migrations]] tag = "v1" new_classes = ["CrawlQueue"]Use from a Worker:
const id = env.QUEUE.idFromName("global"); const stub = env.QUEUE.get(id); const resp = await stub.fetch("http://queue/?action=pop"); const { url } = await resp.json();The Durable Object guarantees that two Workers calling
popsimultaneously get different items (no race condition).Browser Rendering API
For JavaScript-heavy pages, Cloudflare’s Browser Rendering API gives you Chromium in a Worker. It launched in 2024 and stabilized through 2025.
// wrangler.toml binding // [browser] // binding = "MYBROWSER" import puppeteer from "@cloudflare/puppeteer"; export default { async fetch(request, env) { const url = new URL(request.url).searchParams.get("url"); const browser = await puppeteer.launch(env.MYBROWSER); const page = await browser.newPage(); await page.goto(url, { waitUntil: "networkidle0" }); const html = await page.content(); const screenshot = await page.screenshot(); await browser.close(); // Store screenshot in R2 await env.SCREENSHOTS.put(`${Date.now()}.png`, screenshot); return new Response(html, { headers: { "Content-Type": "text/html" }, }); }, };Pricing: $0.20 per browser-minute. A 5-second page render costs ~$0.017. For 1000 pages, that is $17. Compare to running your own browser pool: usually cheaper at high volume but with operational overhead.
Stealth on Workers
Worker fetch uses Cloudflare’s network. The TLS fingerprint is whatever Cloudflare’s outbound HTTP client uses, which is distinctive. Targets that fingerprint TLS see “Cloudflare Worker” patterns.
Mitigations:
- For HTTP-only sites without TLS fingerprinting: standard fetch is fine
- For sites with light fingerprinting: Browser Rendering API uses real Chromium
- For heavy targets: Workers are not the right tool. Use them as orchestration, route the actual fetches through proxied scrapers elsewhere
Cloudflare also offers Smart Placement which routes Workers to a POP near the upstream service, reducing latency. For scraping, you usually want POPs distributed close to your targets.
Subrequest limits
Each Worker invocation can make up to 50 subrequests on Standard plan, 1000 on Unbound. A subrequest is any external fetch, KV operation, D1 query, etc.
For high-volume scraping, this means each Worker invocation can fetch up to 50 pages in parallel. Beyond that, you need to chain invocations:
async function scrapeWithChunking(urls, env) { const CHUNK_SIZE = 30; // leave headroom under 50 for (let i = 0; i < urls.length; i += CHUNK_SIZE) { const chunk = urls.slice(i, i + CHUNK_SIZE); await Promise.all(chunk.map(url => scrapeOne(url, env))); } }If a single chunk takes 30+ seconds CPU time, split into separate Worker invocations triggered by Cron or by Durable Object scheduling.
Cron Triggers for scheduled scraping
Workers support scheduled execution via Cron Triggers in
wrangler.toml:[triggers] crons = ["*/5 * * * *", "0 0 * * *"] # every 5 min and daily at midnightHandler:
export default { async scheduled(event, env, ctx) { if (event.cron === "*/5 * * * *") { // Run every 5 minutes ctx.waitUntil(scrapePriceUpdates(env)); } if (event.cron === "0 0 * * *") { // Daily full crawl ctx.waitUntil(fullCrawl(env)); } }, };ctx.waitUntillets the work continue past the response return, useful for fire-and-forget scrapers.Comparison: Workers vs other serverless for scraping
platform cold start max duration egress cost proxy support browser support Cloudflare Workers <50ms 30s (5min Unbound) free none native Browser Rendering API AWS Lambda 100-3000ms 15 min $0.09/GB yes via container Google Cloud Functions 100-3000ms 9 min $0.12/GB yes via container Azure Functions 200-3000ms 10 min $0.087/GB yes via container Vercel Functions 100-1000ms 60s (Pro) $0.40/GB limited yes Deno Deploy <50ms 50s free yes no For free egress and global edge distribution, Workers and Deno Deploy lead. For long-running tasks and proxy support, Lambda or GCF win. For browser rendering, Workers’ Browser Rendering API or Lambda with custom container.
For broader serverless-scraping patterns in JS, see Deno scraping libraries 2026 reviewed.
Architecture: Workers + Durable Object + R2
A complete distributed scraper:
Cron Trigger (every 1 min) | v +----------------+ | Worker | reads queue, dispatches subrequests +----------------+ | +--------+--------+ | | v v Durable Object Worker subrequests (queue, state) (parallel fetches) | v KV (dedup) D1 (data) R2 (HTML, screenshots)Each Cron tick: Worker reads up to 50 URLs from the Durable Object queue, fetches them in parallel, parses, writes results to D1 and R2, marks URLs as visited in KV. If queue still has items, schedule another invocation immediately.
This pattern handles tens of thousands of URLs per hour on Workers Standard, scales to millions on Unbound.
Cost analysis
A scraper doing 1 million page fetches per month:
component cost Workers requests (1M) $0.30 Workers CPU time varies, ~$5-20 KV reads (visited check) $0.50 D1 writes (results) $1-3 R2 storage (HTML at 50 KB avg) $0.75 Durable Object requests $0.15 Browser Rendering (10% of pages, 5 sec each) $1,000 Total without browser ~$10/month Total with browser on 10% of pages ~$1,010/month Without browser rendering, Workers are extremely cheap. With browser rendering, they are still competitive but no longer the absolute bargain. For pages that need browser rendering at scale, consider running Playwright on dedicated VMs and reserving Workers for HTTP-only flows.
Common pitfalls
- Cold storage state on first invocation: Durable Objects start empty; handle nil/empty cases
- HTMLRewriter is streaming, not DOM: cannot do complex selector queries
- No npm packages with native code: pure JS only
- Subrequest limit: hits silently when exceeded, your fetch returns an error
- CPU limit applies to async work too: even waiting for a fetch counts if your Worker is processing
- Time limit measured in CPU time: 30 seconds CPU != 30 seconds wall clock
- No persistent disk: cannot save SQLite files, must use D1 or KV
For the Cloudflare Workers limits reference, see Workers limits.
Operational checklist
For production scrapers on Workers in 2026:
- Wrangler 3+ for deploys
- Workers Unbound plan if you need >30s CPU or >50 subrequests
- Durable Objects for queues and rate limits
- KV for dedup and lightweight state
- D1 or R2 for results storage
- Cron Triggers for scheduling
- Monitor CPU time, subrequest count, error rate per Worker
- Use Workers Logpush to stream logs to R2 or external SIEM
- Reserve Browser Rendering API for pages that truly need JS
- For TLS-fingerprinted targets, route through external proxy infrastructure
- Test with
wrangler dev --remotefor true edge testing
FAQ
Q: can I use proxies with Workers?
Not natively. Workers fetch from Cloudflare’s network. To use proxies, you would need to route to a proxy service via fetch (a custom proxy that accepts HTTPS and forwards), which is awkward. For proxy-required scraping, run your scrapers elsewhere.Q: how does Worker fetch’s TLS fingerprint look?
Distinct from any browser. Cloudflare’s outbound HTTP client has its own JA4. Targets that check TLS fingerprints can identify it. For TLS-sensitive targets, do not use Workers for the fetch.Q: is Browser Rendering API a real Chrome?
Yes, it runs Chromium in Cloudflare’s infrastructure. Your Worker connects to it via the puppeteer-compatible API. It supports stealth patches but is metered.Q: can I do long-running scraping on Workers?
Not in a single invocation. Use Durable Objects to break work into small chunks, with each Worker invocation handling one chunk. Coordinate via Cron or self-scheduled triggers.Q: how do Workers compare to Vercel Edge Functions for scraping?
Workers have lower cold start and free egress; Vercel has Edge Functions in similar shape but with usage-based pricing including egress. For raw scraping cost at scale, Workers are cheaper. For Vercel projects already using their platform, Edge Functions integrate natively.Common pitfalls in production Workers scraping
The first failure mode is the subrequest fan-out cliff. Workers Standard caps subrequests at 50 per invocation; Workers Unbound raises this to 1000. A scraper that processes a category page and queues 60 product fetches from a single Worker invocation hits the cap silently: the 51st fetch returns an error in the response object but does not throw. Your loop continues, your error counter never increments because you assumed
fetch()would throw, and you end up with 49 successful fetches and 11 silently dropped requests. The fix is two-part: first, always checkresponse.okandresponse.statusafter every fetch; second, batch outbound fetches into chunks of 40 (leaving headroom for retries) and queue overflow into the Durable Object for the next Cron tick.The second pitfall is HTMLRewriter buffering on slow upstreams. HTMLRewriter is streaming, but if your handler does any async work inside an element callback, it pauses the stream. A handler that fetches a related URL on every
<a href>element it encounters effectively serializes the entire HTML parse, turning a 200ms streaming parse into a 30+ second one (one fetch per anchor). The fix is to collect the URLs synchronously into an array during the parse, then dispatch fetches in parallel after the parse completes:const collectedUrls = []; const rewriter = new HTMLRewriter().on("a[href]", { element(el) { collectedUrls.push(el.getAttribute("href")); // sync only }, }); await rewriter.transform(response).text(); // Now fan out const subResponses = await Promise.all( collectedUrls.slice(0, 40).map((u) => fetch(new URL(u, baseUrl))) );The third pitfall is Durable Object hibernation losing in-memory state. DOs hibernate after about 10 seconds of inactivity, and any state stored in instance variables (not in
state.storage) is lost on wake. Scrapers that maintain a “currently processing” set inthis.processing = new Set()find that the set is empty after every cron-triggered wake, leading to duplicate processing. Always persist coordination state viastate.storage.put()and re-hydrate viastate.storage.get()on every method entry. Hibernation is documented but easy to forget when your localwrangler devkeeps state in memory across reloads.Real-world example: 10M-URL crawl with $40 monthly cost
A scraper team built a price-monitoring system that fetched 10 million product URLs per month across 200 ecommerce sites. The architecture used Workers Cron + Durable Objects + KV + D1 + R2:
// cron.js — runs every minute export default { async scheduled(event, env, ctx) { const queueDO = env.QUEUE_DO.get(env.QUEUE_DO.idFromName("global")); const batch = await queueDO.fetch("https://internal/dequeue?count=40").then(r => r.json()); if (!batch.urls.length) return; const results = await Promise.all(batch.urls.map(async (url) => { try { const r = await fetch(url, { headers: { "user-agent": "Mozilla/5.0 ..." }, cf: { cacheTtl: 0 }, // never cache, always fresh }); if (!r.ok) return { url, error: `status ${r.status}` }; const html = await r.text(); const price = extractPrice(html); // sync HTMLRewriter elsewhere return { url, price, fetched_at: Date.now() }; } catch (e) { return { url, error: e.message }; } })); // Write results to D1 in one batched insert const stmt = env.DB.prepare( "INSERT INTO prices (url, price, fetched_at) VALUES (?, ?, ?)" ); await env.DB.batch(results .filter(r => r.price) .map(r => stmt.bind(r.url, r.price, r.fetched_at)) ); }, };Monthly billing breakdown:
- Workers requests: 14.4M (43,200 cron ticks at 40 fetches + 14M subrequests) = $4.80
- Workers CPU time at avg 80ms per invocation = $11.50
- Durable Object requests = $1.20
- D1 writes (10M rows) = $15
- KV reads (dedup checks) = $5
- R2 storage (sampled raw HTML, 100GB) = $1.50
Total: $39 per month for 10M monitored URLs. The same workload on AWS Lambda + RDS would have cost approximately $850 per month, dominated by RDS instance fees and Lambda invocation costs. The lesson: Workers wins decisively when the workload fits its constraints (no proxies needed, sub-second per page, results structured enough for D1).
Detection: when Workers are the wrong choice
Five signals that your scraping workload should NOT live on Workers:
- Per-request proxy required: Workers cannot rotate through residential proxy pools efficiently. Move to Lambda or VMs.
- Long-running JS challenges: Cloudflare’s own Under Attack mode takes 5-10 seconds, and other JS challenges take similar time. Workers Unbound max is 5 minutes but CPU time is metered separately. Use Browserbase or VM-based Playwright.
- Heavy data parsing: A 5MB HTML page parsed via DOMParser easily exceeds the 30s Workers Standard CPU budget. HTMLRewriter handles streaming HTML but is awkward for non-trivial extraction.
- Stateful sessions across many requests: Cookies and login flows that span dozens of requests work better in long-lived processes.
- Custom TLS fingerprinting: Workers cannot impersonate Chrome’s TLS handshake. Targets that check JA4 see Cloudflare’s outbound fingerprint instead.
If any two of these apply, run your scraper on Fargate, EKS, or self-hosted infrastructure instead.
Wrapping up
Cloudflare Workers are a niche but powerful scraping platform when the workload fits: high volume, distributed, HTTP-light, with state in KV/D1/Durable Objects. Browser Rendering API closes the JS gap at the cost of metered pricing. Pair this with our scrapers vs Playwright integration patterns and Deno scraping libraries for the full serverless picture, and browse the dev-tools-projects category on DRT for related infrastructure deep-dives.
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Scrapy + Playwright integration in 2026
Scrapy + Playwright integration in 2026
Scrapy + Playwright integration is the standard answer when Scrapy’s speed and pipeline ergonomics meet pages that need a real browser to render. Scrapy alone runs at thousands of pages per second through asynchronous Twisted callbacks but cannot execute JavaScript. Playwright can drive a real browser through any page but is a single-page-at-a-time tool that does not give you Scrapy’s middleware, item pipelines, or deduplication. The
scrapy-playwrightplugin bridges them: Scrapy still handles the orchestration, scheduling, and pipelines, but pages route through Playwright when needed.This guide covers scrapy-playwright 0.0.40+ on Scrapy 2.11+ in 2026, the setup steps, the page coroutines pattern, proxy and stealth integration, and production patterns that scale. Code is Python 3.12 throughout. By the end you will have a Scrapy project that can mix HTML-only requests (fast) and Playwright-rendered requests (slow but JS-capable) in one spider, with shared middleware and pipelines.
Why this combination wins
Scrapy alone is unbeatable for HTML-only scraping at scale. Its async model, request prioritization, deduplication, and pipeline architecture are mature. The weakness is that any JavaScript-rendered page returns empty HTML.
Playwright alone handles JS perfectly but has no concept of crawl orchestration. You write your own request queue, deduplication, retry logic, and item processing.
scrapy-playwright lets each page in a Scrapy spider opt into Playwright via a metadata flag. Pages without the flag stay as fast HTML requests. Pages with the flag route through a Playwright pool, render fully, and return rendered HTML to your callback as if Scrapy fetched it directly.
For Scrapy’s official docs, see Scrapy 2.11+ documentation. For Playwright’s, see Playwright Python documentation.
Installation
pip install scrapy scrapy-playwright playwright playwright install chromiumVerify versions:
scrapy version # 2.11.0 or later python -c "import scrapy_playwright; print(scrapy_playwright.__version__)" # 0.0.40 or laterProject setup
Create a Scrapy project:
scrapy startproject dynamic_scraper cd dynamic_scraperEdit
dynamic_scraper/settings.pyto enable scrapy-playwright:# settings.py DOWNLOAD_HANDLERS = { "http": "scrapy_playwright.handler.ScrapyPlaywrightDownloadHandler", "https": "scrapy_playwright.handler.ScrapyPlaywrightDownloadHandler", } TWISTED_REACTOR = "twisted.internet.asyncioreactor.AsyncioSelectorReactor" PLAYWRIGHT_BROWSER_TYPE = "chromium" PLAYWRIGHT_LAUNCH_OPTIONS = { "headless": True, "args": [ "--disable-blink-features=AutomationControlled", "--disable-features=IsolateOrigins", ], } # How many concurrent Playwright contexts to maintain PLAYWRIGHT_MAX_CONTEXTS = 8 PLAYWRIGHT_DEFAULT_NAVIGATION_TIMEOUT = 30000 # Reasonable defaults for mixed crawls CONCURRENT_REQUESTS = 16 CONCURRENT_REQUESTS_PER_DOMAIN = 4 DOWNLOAD_DELAY = 0 RETRY_TIMES = 3 # Standard middleware for header rotation, etc DOWNLOADER_MIDDLEWARES = { "scrapy.downloadermiddlewares.useragent.UserAgentMiddleware": None, "scrapy_user_agents.middlewares.RandomUserAgentMiddleware": 400, "dynamic_scraper.middlewares.ProxyMiddleware": 410, } # Item pipeline (whatever you need) ITEM_PIPELINES = { "dynamic_scraper.pipelines.JsonExportPipeline": 300, }The download handlers route every HTTP request through scrapy-playwright. Pages without the
playwrightmeta flag are still fetched via regular HTTP (scrapy-playwright detects this automatically), so you do not pay the browser cost for pages that do not need it.A first spider mixing HTML and Playwright requests
Most real spiders mix request types. The product listing might be static HTML, but the product detail might require JavaScript. scrapy-playwright handles this cleanly:
# spiders/products.py import scrapy from scrapy_playwright.page import PageMethod class ProductSpider(scrapy.Spider): name = "products" allowed_domains = ["example.com"] start_urls = ["https://example.com/products"] def parse(self, response): # Listing page is plain HTML, no Playwright needed for product_url in response.css("a.product-link::attr(href)").getall(): yield response.follow( product_url, callback=self.parse_product, meta={ "playwright": True, "playwright_include_page": False, "playwright_page_methods": [ PageMethod("wait_for_selector", "div.product-detail"), ], }, ) next_page = response.css("a.next::attr(href)").get() if next_page: yield response.follow(next_page, callback=self.parse) def parse_product(self, response): yield { "title": response.css("h1.product-title::text").get(), "price": response.css("span.price-current::text").get(), "stock": response.css("div.stock-info::text").get(), "description": response.css("div.product-description").get(), }Key points:
- The listing page is fetched normally (no
playwright: Truein meta) - Product detail pages are fetched via Playwright (
playwright: True) playwright_page_methodsruns on the Playwright page before returning the HTMLwait_for_selectorensures the JavaScript-rendered detail is present before scrapy-playwright captures the HTML
This pattern keeps the spider’s overall structure conventional while opting specific pages into the heavyweight rendering path.
Interacting with the page
Some scraping requires interaction (click a “Show more” button, scroll to load infinite content, fill a search form). For this, request the actual Playwright Page object back via
playwright_include_page=True:import scrapy from scrapy_playwright.page import PageMethod class InfiniteScrollSpider(scrapy.Spider): name = "infinite" start_urls = ["https://example.com/feed"] def start_requests(self): for url in self.start_urls: yield scrapy.Request( url, meta={ "playwright": True, "playwright_include_page": True, "playwright_page_methods": [ PageMethod("wait_for_selector", "article.feed-item"), ], }, callback=self.parse_feed, errback=self.errback_close_page, ) async def parse_feed(self, response): page = response.meta["playwright_page"] # Scroll to load more items for _ in range(5): await page.evaluate("window.scrollBy(0, document.body.scrollHeight)") await page.wait_for_timeout(2000) html = await page.content() await page.close() # Parse the now-loaded HTML with Scrapy selectors from scrapy.http import HtmlResponse new_response = HtmlResponse(url=response.url, body=html, encoding="utf-8") for article in new_response.css("article.feed-item"): yield { "title": article.css("h2::text").get(), "url": article.css("a::attr(href)").get(), "summary": article.css("p.summary::text").get(), } async def errback_close_page(self, failure): page = failure.request.meta.get("playwright_page") if page: await page.close()The
playwright_include_page=Truemeans the Page object is attached to the response. Your callback can interact with it (scroll, click, wait) before extracting HTML. Always close the page in your callback or errback to avoid leaking browser contexts.Proxy integration
Pass proxies to Playwright either at the launch level (one proxy for all contexts) or per-context (different proxy per request). Per-context is the more flexible pattern.
# settings.py addition PLAYWRIGHT_CONTEXTS = { "default": { "proxy": { "server": "http://squid.internal:3128", "username": "scraper_user", "password": "secret", }, }, }For per-request proxies via a custom middleware:
# middlewares.py import random class ProxyRotationMiddleware: PROXIES = [ "http://user1:pass1@proxy1.provider.com:8080", "http://user2:pass2@proxy2.provider.com:8080", "http://user3:pass3@proxy3.provider.com:8080", ] def process_request(self, request, spider): if request.meta.get("playwright"): # For Playwright requests, set the context with a specific proxy proxy = random.choice(self.PROXIES) user_pass, host_port = proxy.split("//")[1].split("@") user, password = user_pass.split(":") host, port = host_port.split(":") request.meta["playwright_context"] = f"proxy_{hash(proxy)}" request.meta["playwright_context_kwargs"] = { "proxy": { "server": f"http://{host}:{port}", "username": user, "password": password, }, } else: # For regular HTTP requests, set the standard proxy meta request.meta["proxy"] = random.choice(self.PROXIES)scrapy-playwright caches contexts by name, so reusing the same proxy uses the same context. This avoids spawning a new browser context per request, which is expensive.
Stealth: integrating patchright
For sites that fingerprint, use patchright (Playwright stealth fork) instead of vanilla Playwright. patchright is a drop-in replacement, so you can swap it in via setting the playwright module:
# In your settings.py or as an environment variable import patchright as playwright_module PLAYWRIGHT_BROWSER_TYPE = "chromium" # scrapy-playwright will use whatever playwright module is installedOr install patchright as the playwright package (it shadows vanilla playwright):
pip install patchright playwright install chromiumAfter install, scrapy-playwright automatically uses patchright’s launch logic, which applies stealth patches.
For fine-grained stealth on a per-request basis, inject scripts via
init_script:yield scrapy.Request( url, meta={ "playwright": True, "playwright_context_kwargs": { "user_agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 " "(KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36", }, "playwright_page_init_script": """ Object.defineProperty(navigator, 'webdriver', { get: () => undefined }); Object.defineProperty(navigator, 'plugins', { get: () => [1, 2, 3] }); """, }, )For the full picture on browser fingerprinting, see canvas fingerprinting bypass and WebGL fingerprinting bypass.
Performance: how much does Playwright slow you down
Throughput comparison on a single worker:
request type requests/sec pure Scrapy HTML 200-500 scrapy-playwright (cached context, simple page) 5-10 scrapy-playwright (new context, complex SPA) 1-2 scrapy-playwright with full humanization 0.3-0.5 The cost is real. Use Playwright only for pages that need it. The mixed pattern (HTML for listings, Playwright for details) is the right balance for most sites.
To scale Playwright throughput:
- Increase
PLAYWRIGHT_MAX_CONTEXTS(each context costs ~100 MB RAM) - Reuse contexts across requests by giving them stable names
- Run multiple Scrapy instances on different machines
- Keep navigation timeout tight (30 seconds is usually enough)
Comparison: scrapy-playwright vs alternatives
approach strengths weaknesses scrapy-playwright mixed HTML/JS in one project, native Scrapy pipelines adds Playwright overhead even for simple sites scrapy-splash older, lighter than Playwright Splash is essentially abandoned, JS engine is dated scrapy + selenium-wire works slow, fragile scrapy + standalone Playwright service clean separation extra service to operate pure Playwright most JS-capable no Scrapy pipelines, write your own everything Crawlee (Node) similar pattern in Node ecosystem requires switching off Python For most Python teams in 2026, scrapy-playwright is the right pick. For Node teams, Crawlee. For very simple JS sites, scrapy-splash still works but is on its way out.
For the alternative Crawlee path, see Scrapy Cloud vs Crawlee Cloud in 2026.
Item pipelines and Playwright
Item pipelines work identically whether the request was HTML-only or Playwright. The pipeline sees a Scrapy
Item(or dict) and processes it. No changes needed:# pipelines.py import json from datetime import datetime class JsonExportPipeline: def open_spider(self, spider): self.file = open(f"output/{spider.name}_{datetime.now():%Y%m%d_%H%M%S}.jsonl", "w") def close_spider(self, spider): self.file.close() def process_item(self, item, spider): line = json.dumps(dict(item)) + "\n" self.file.write(line) return itemThis is one of the main wins of scrapy-playwright over rolling your own: you get to keep all your existing Scrapy pipelines and middleware.
Common patterns
Wait for specific elements before extracting:
yield scrapy.Request( url, meta={ "playwright": True, "playwright_page_methods": [ PageMethod("wait_for_selector", "div.product-loaded"), PageMethod("wait_for_load_state", "networkidle"), ], }, )Click a button to load content:
yield scrapy.Request( url, meta={ "playwright": True, "playwright_page_methods": [ PageMethod("click", "button.show-more"), PageMethod("wait_for_selector", "div.expanded-content"), ], }, )Take a screenshot for debugging:
yield scrapy.Request( url, meta={ "playwright": True, "playwright_page_methods": [ PageMethod("screenshot", path="debug.png", full_page=True), ], }, )Intercept network requests:
async def parse(self, response): page = response.meta["playwright_page"] # Capture all XHR responses captured_data = [] page.on("response", lambda r: captured_data.append(r.url)) await page.wait_for_load_state("networkidle") await page.close() yield {"all_xhr_urls": captured_data}Production deployment
A production scrapy-playwright deployment looks like:
- Compute: container with Chromium installed (use playwright-base images)
- Concurrency: tune CONCURRENT_REQUESTS based on RAM (each Playwright context is ~100 MB)
- Proxy: routed through Squid or commercial pool
- Stealth: patchright as drop-in
- Monitoring: Scrapy stats + Playwright context counter
- Persistence: items to a database or queue, not just files
- Scheduling: scrapyd, scrapy-cluster, or Airflow
A reasonable container Dockerfile:
FROM mcr.microsoft.com/playwright/python:v1.45.0-jammy WORKDIR /app COPY requirements.txt . RUN pip install --no-cache-dir -r requirements.txt COPY . . ENV PLAYWRIGHT_BROWSERS_PATH=/ms-playwright CMD ["scrapy", "crawl", "products"]Use the playwright-python base image to skip installing Chromium and dependencies separately.
Operational checklist
For production scrapy-playwright deployments in 2026:
- Scrapy 2.11+, scrapy-playwright 0.0.40+
- Use playwright-python base image for containers
- patchright for stealth
- Per-request opt-in to Playwright via meta flag
- Always close pages in callbacks and errbacks
- Use named contexts to reuse across requests
- Tune CONCURRENT_REQUESTS based on RAM
- Set navigation timeouts (30s default is reasonable)
- Log per-spider stats including Playwright vs HTML request count
- Pair with proxy rotation middleware
- Monitor RAM usage closely (Playwright contexts leak if not closed)
FAQ
Q: can I use Playwright with Scrapy without scrapy-playwright?
You can, but it is painful. You would have to write your own download handler, manage the browser lifecycle, and integrate with Scrapy’s async model. scrapy-playwright handles all this for you.Q: what about scrapy-splash?
Splash is essentially unmaintained as of 2024-2025. The JS engine is older and many modern SPAs do not render correctly. Use scrapy-playwright unless you have legacy reasons to stay on Splash.Q: how do I handle Playwright authentication and cookies?
Pass cookies via the request meta or set them on the context:meta={"playwright": True, "playwright_context_kwargs": {"storage_state": "auth.json"}}auth.jsonis generated by saving Playwright’scontext.storage_state()after login.Q: can I run scrapy-playwright on AWS Lambda?
Technically yes via Playwright’s Lambda layers, but the cold start is brutal (10+ seconds per invocation just to launch Chromium). For Lambda, prefer dedicated browser services like Browserbase or run scrapy-playwright on Fargate or EKS instead.Q: does scrapy-playwright support Firefox?
Yes. SetPLAYWRIGHT_BROWSER_TYPE = "firefox"and runplaywright install firefox. Most patches work on Firefox too, though some stealth libraries are Chromium-focused.Common pitfalls in production scrapy-playwright
The first failure mode that catches teams off guard is the page-object leak. scrapy-playwright passes the open
Pageto your callback viaresponse.meta["playwright_page"], but if your parse function raises an exception or yields requests without closing the page, the browser context retains a reference. After 50-100 leaked pages, Chromium hits its per-context limit (typically 30 tabs depending on RAM) and new requests stall waiting for tab slots. The fix is a try/finally pattern in every parse method that touchesplaywright_page:async def parse_product(self, response): page = response.meta.get("playwright_page") try: await page.wait_for_selector(".product-loaded", timeout=10000) title = await page.text_content("h1") yield {"title": title} except Exception as e: self.logger.error(f"parse failed: {e}") raise finally: if page: await page.close()Add an errback that also closes the page on download failure, otherwise pages leak from network errors that never reach your parse callback.
The second pitfall is the headers-vs-Playwright disconnect. Setting
headerson ascrapy.Requestdoes not automatically pass them to Playwright whenplaywright=True. Scrapy treats those headers as the eventual download request, but Playwright bypasses Scrapy’s downloader entirely and uses its own. The result: your User-Agent rotation middleware appears to set a Chrome 124 UA but Playwright launches with whatever UA the browser instance has. The fix is to set headers viaplaywright_context_kwargson each request:yield scrapy.Request( url, meta={ "playwright": True, "playwright_context_kwargs": { "user_agent": rotated_ua, "extra_http_headers": rotated_headers, }, }, )Each new context spawn now gets the rotated UA and headers. Beware: spawning a new context per request defeats Playwright’s connection reuse, so pair this with named contexts to amortize the cost across same-UA requests.
The third pitfall is silent JavaScript navigation that bypasses Scrapy’s URL tracking. When a page does
window.location.href = "/next-page"mid-load, Playwright follows it and ends up at a URL different from what you originally requested. Scrapy’s response.url reflects the post-navigation URL, but your duplicate-detection middleware only saw the original URL. You can end up scraping the same final page repeatedly through different entry-point URLs. The fix is to track final URLs in your DupeFilter:from scrapy.dupefilters import RFPDupeFilter import hashlib class FinalUrlDupeFilter(RFPDupeFilter): def request_seen(self, request): # If response has been received, dedupe on response.url too final_url = request.meta.get("playwright_final_url") if final_url: fp = hashlib.sha256(final_url.encode()).hexdigest() if fp in self.fingerprints: return True self.fingerprints.add(fp) return super().request_seen(request)Set
playwright_final_urlin your parse callback after capturingpage.url, then re-yield the request through the dedupe filter.Real-world example: 50,000-product crawl with mixed HTML and Playwright
A scrapy-playwright project crawled an electronics retailer with 50,000 products across 800 category pages. Initial implementation used Playwright for everything and took 18 hours per full crawl with 90 percent CPU usage on a 16-core machine. The optimization that cut this to 2.5 hours was a tiered request strategy that classified URL patterns and used the cheapest method per pattern:
class TieredSpider(scrapy.Spider): name = "products_tiered" def start_requests(self): # Category pages: pure HTML, server-rendered for cat_url in self.category_urls: yield scrapy.Request(cat_url, callback=self.parse_category) def parse_category(self, response): # Extract product URLs from server-rendered HTML for url in response.css(".product-link::attr(href)").getall(): full_url = response.urljoin(url) # Tier 1: standard product page (HTML works) if "/p/" in full_url: yield scrapy.Request(full_url, callback=self.parse_product_html) # Tier 2: SPA product detail (Playwright needed) elif "/spa-product/" in full_url: yield scrapy.Request( full_url, meta={ "playwright": True, "playwright_page_methods": [ PageMethod("wait_for_selector", ".price-loaded"), ], }, callback=self.parse_product_playwright, ) def parse_product_html(self, response): yield { "url": response.url, "title": response.css("h1::text").get(), "price": response.css(".price::text").get(), } async def parse_product_playwright(self, response): page = response.meta["playwright_page"] try: title = await page.text_content("h1") price = await page.text_content(".price") yield {"url": response.url, "title": title, "price": price} finally: await page.close()Of the 50,000 products, only 8,000 needed Playwright (the SPA product pages). The remaining 42,000 went through pure Scrapy HTML at 200+ requests/second. Playwright handled the 8,000 SPA pages at 5 requests/second. Total throughput: 5.5 hours for the HTML tier and 27 minutes for the SPA tier, running concurrently in 2.5 hours total. The lesson: classify your URLs by render type and route accordingly. Default-to-Playwright is the most expensive choice you can make.
Comparison: scrapy-playwright settings tuning by site type
Different site types need different tuning profiles. A reference table from a 2026 production deployment:
site type CONCURRENT_REQUESTS PLAYWRIGHT_MAX_CONTEXTS nav timeout wait strategy ecommerce SPA 16 8 30s wait_for_selector on price news article 32 16 15s wait_for_load_state domcontentloaded listing with infinite scroll 8 4 60s manual scroll + wait_for_response dashboard behind login 4 2 45s wait_for_url + wait_for_selector pricing page (heavy JS) 16 8 30s wait_for_function on data-loaded attr For listing pages with infinite scroll, use a manual scroll loop:
async def scroll_until_done(page, max_scrolls=20): for i in range(max_scrolls): prev_height = await page.evaluate("document.body.scrollHeight") await page.evaluate("window.scrollTo(0, document.body.scrollHeight)") await page.wait_for_timeout(1500) new_height = await page.evaluate("document.body.scrollHeight") if new_height == prev_height: break # no more content loadedWithout the scroll-until-done pattern, you get only the first viewport’s worth of items even when the listing has 500+. Pair with a per-spider
MAX_SCROLL_ITERATIONSsetting so a runaway page does not loop forever.Memory profiling: detecting Playwright leaks
Production scrapy-playwright deployments suffer from RAM growth that takes hours to manifest. The cause is almost always context reuse without bounded lifetime. Each long-lived context accumulates DOM nodes, IndexedDB entries, and service worker state. After 4-6 hours of constant scraping through one context, RAM usage doubles. The detection pattern:
import psutil import os class MemoryMonitorMiddleware: def __init__(self): self.process = psutil.Process(os.getpid()) self.baseline_mb = self.process.memory_info().rss / 1024 / 1024 self.requests_processed = 0 def process_response(self, request, response, spider): self.requests_processed += 1 if self.requests_processed % 100 == 0: current_mb = self.process.memory_info().rss / 1024 / 1024 growth = current_mb - self.baseline_mb spider.logger.info( f"requests={self.requests_processed} " f"rss={current_mb:.0f}MB growth={growth:.0f}MB" ) if growth > 2000: # 2GB growth, recycle contexts spider.logger.warning("memory bloat detected, recycling contexts") # Trigger context recycling in your context manager return responseRecycle contexts every 1000-2000 requests by closing them and letting scrapy-playwright spawn fresh ones. This caps RAM growth at the cost of one cold-context launch per recycle (about 800ms). For long-running spiders, this is a worthwhile trade.
Wrapping up
Scrapy + Playwright is the right combination for any Python scraping project that mixes simple HTML pages with JavaScript-heavy pages. scrapy-playwright glues them cleanly enough that you keep all of Scrapy’s pipeline ergonomics while getting Playwright’s rendering capability where you need it. Pair this guide with our Scrapy Cloud vs Crawlee Cloud and best Python scraping libraries 2026 writeups, and browse the framework-tutorials category on DRT for related tutorials.
- The listing page is fetched normally (no
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Self-hosted proxy infrastructure: complete 2026 guide
Self-hosted proxy infrastructure: complete 2026 guide
Self-hosted proxy infrastructure is a category that ranges from “I run Squid in front of five purchased upstream proxies” to “I operate a 200-modem mobile proxy farm with ISP business contracts and four-9s uptime.” This guide is about the latter end of the spectrum: the build that actually saves money compared to buying from Bright Data or Oxylabs at scale, the operational reality of running it, and the break-even point where self-hosting starts paying off.
The numbers in this guide come from operating real proxy infrastructure on the SMP (Singapore Mobile Proxy) and similar farms in the Singapore-Malaysia region. The pricing, hardware choices, and ISP dynamics are 2026 reality. If you are scraping under 1 million pages per month, self-hosting is probably not worth it. Above 10 million, the unit economics are compelling. In between is the gray zone where it depends on your engineering capacity.
Why self-host
The case for self-hosted proxies in 2026:
- Cost: at scale, self-hosted mobile proxies cost $0.30-$1 per GB versus $5-15/GB from premium vendors
- Control: you choose the ISPs, IP ranges, geo distribution, and rotation behavior
- Reliability: no upstream vendor outages affecting your business
- Privacy: your traffic does not pass through a third-party gateway that logs everything
- Customer billing: you can resell capacity if you have spare throughput
The case against:
- Capex: hardware, racks, network equipment cost upfront ($50k+ for a serious build)
- Opex: data plans, electricity, internet uplink, maintenance hours
- ISP relationships: requires business contracts, sometimes legal entity in the country
- 24/7 ops: things break at 3am, you fix them
- Capacity inflexibility: cannot quickly add 500 more IPs the way Bright Data can
Most teams should buy proxies. Self-hosting is for the small number of teams whose volume justifies the operational burden.
Architecture: the SMP-style mobile proxy farm
A typical mid-scale mobile proxy farm:
+ customers (scrapers, ad-verification, OSINT) + | | HTTPS to public IP v +-------------------------+ | Edge proxy (Squid + | | ProxySmart controller) | +-------------------------+ | | private 10.x routing v +-------+-------+-------+-------+ | | | | | server1 server2 server3 server4 ... | | | | | | USB | USB | USB | USB | v v v v v modem1 modem2 modem3 modem4 modem5 ... (LTE) (LTE) (LTE) (LTE) (LTE) | | | | | v v v v v ISP A ISP B ISP A ISP C ISP B (carrier APNs)Each modem produces one mobile IP via PPP-over-LTE through the carrier’s APN. The server hosts a process that exposes that modem as an HTTP/SOCKS5 port to the controller. The controller assigns ports to customers, handles rotation, and meters usage.
This pattern scales modularly: add a server with 50 modems, expose 50 more ports, customers see them as additional capacity. Each modem is one IP with full carrier-grade NAT obfuscation, which is the reason mobile IPs are valuable for scraping (they look like millions of real users sharing the carrier’s NAT pool).
Hardware: per-server build
Per-server hardware for a 50-modem build:
component spec purpose chassis 4U server, 12-bay or rackmount mining frame physical housing CPU Intel i5-12500 or Ryzen 5 5600 enough for 50 modem PPP daemons RAM 32 GB DDR4 one PPP daemon per modem, ~500 MB each storage 500 GB NVMe SSD OS, logs, modem state USB hubs 4x 16-port industrial USB 3.0 hubs 64 USB ports total modems 50x Huawei E3372 or similar 4G/LTE dongles the actual modems SIM cards 50x carrier SIMs with data plans network access network 2x 1 Gbit Ethernet (LACP) uplink to switch PSU redundant 850W reliability Cost per server: roughly $4,000-6,000 in hardware plus $300-500/month in SIM data plans (varies by country and plan size).
For the full multi-server build:
- 4-server cluster: ~$20,000 hardware + $1,500/month opex
- Yields 200 mobile IPs
- Throughput: ~10 Mbit/s per modem aggregate, so 2 Gbit/s peak across the farm
- Bandwidth budget: usually 50-200 GB per modem per month (carrier-dependent)
Modems are the failure-prone component. Plan for 5-10% modem replacement per year. Keep spare modems and SIMs on hand.
Software stack
Each server runs:
- Linux: Ubuntu 22.04 LTS or 24.04 LTS (most modem driver compatibility)
- PPP daemon: pppd per modem with carrier-specific APN config
- ProxySmart: per-modem HTTP/SOCKS proxy daemon exposing the PPP IP as a port
- Controller agent: communicates with the central controller for port assignment, rotation, telemetry
ProxySmart specifically wraps each modem’s PPP interface and exposes it as an HTTP CONNECT proxy. Customers connect to a port (e.g.,
server2.example.com:8123) and traffic egresses through the modem’s mobile IP.For DNS within the proxy farm, run a local resolver (unbound or dnsmasq) so that DNS queries do not leak to ISP resolvers, which can throttle or log them.
Network: ISP business contracts
The hardest part of self-hosting mobile proxies is not the technology, it is the SIM card supply. Personal-line carriers throttle or terminate SIMs that are clearly used for proxying. You need:
- Business SIM contracts: a corporate account with 50+ lines, possibly negotiated bulk pricing
- Data plans: typically 100-200 GB/month per line, billed as a corporate package
- APN access: business APN (sometimes different from consumer APN)
- Rotating contract terms: some carriers prohibit “automation” in their AUP; you need terms that allow this use
Country-specific dynamics in 2026:
region ISP-friendliness typical contract Singapore high (Singtel, Starhub, M1 all have business plans) $30-50 per 100 GB Malaysia medium (Maxis, Digi, Celcom; some restrictions) $20-40 per 100 GB Indonesia medium (Telkomsel, Indosat; data caps strict) $15-30 per 100 GB Thailand high (AIS, Truemove, dtac all have plans) $25-45 per 100 GB US low (Verizon, AT&T, T-Mobile have hostile AUPs) $40-80 per 100 GB Europe varies (Vodafone, Orange friendlier; Telekom hostile) $20-50 per 100 GB Without a business relationship, the SIMs get shut down within weeks of heavy use. With a relationship, they last months or years.
Carrier rotation: rebooting modems for fresh IPs
Mobile IPs rotate on PPP reconnection. To get a new IP:
- Send AT command to modem to reset
- Wait for PPP to drop and reestablish
- New IP is assigned by the carrier
Time to rotate: 10-30 seconds per modem. Customers see this as a “rotate” API call that returns a new IP within 30 seconds.
# Sketch of modem rotation script import subprocess import time def rotate_modem(modem_id: int) -> str: # Send AT command via the modem's serial interface subprocess.run( ["echo", "AT+CFUN=4", ">", f"/dev/ttyUSB{modem_id}_at"], shell=True, ) time.sleep(2) subprocess.run( ["echo", "AT+CFUN=1", ">", f"/dev/ttyUSB{modem_id}_at"], shell=True, ) # Wait for PPP to come back up for _ in range(30): time.sleep(1) ip = subprocess.check_output( ["ip", "addr", "show", f"ppp{modem_id}"] ).decode() if "inet " in ip: new_ip = ip.split("inet ")[1].split("/")[0] return new_ip raise TimeoutError(f"modem {modem_id} did not reconnect")In production, ProxySmart handles this via a REST API exposed per modem. Customers call
POST /rotate/<port_token>and get a fresh IP within 30 seconds.Customer-facing API
A typical customer interaction:
# Customer's scraper uses the proxy port curl -x http://user:pass@proxy.example.com:8123 https://target.example.com # When they need rotation curl -X POST -H "Authorization: Bearer api_key" \ https://proxy.example.com/api/v1/rotate/port_8123 # Check current IP curl -x http://user:pass@proxy.example.com:8123 https://api.ipify.orgThe controller exposes a REST API for customer self-service:
POST /api/v1/rotate/<port>: trigger rotationGET /api/v1/status/<port>: current IP, data used, plan limitPOST /api/v1/swap/<port>: swap to a different modem (different ISP/IP range)GET /api/v1/usage: per-customer billing info
For an example of this kind of platform, see Singapore Mobile Proxy which exposes mobile proxies via this pattern.
Costs and break-even
Real numbers for a 200-modem mobile farm in Singapore:
line item monthly cost SIM data plans (200 lines, 100 GB each) $7,000 Server power (4 servers, 24/7) $400 Internet uplink (1 Gbit business) $300 Rack space (colo, 2U each * 4) $500 Hardware amortization ($20k over 36 months) $560 Engineering time (1 day/week) $2,000 Total $10,760/month Capacity: 200 IPs * 100 GB/month = 20,000 GB/month total bandwidth. At a customer price of $1.50/GB, revenue is $30,000/month at full utilization. Margin: 65% gross.
For comparison, buying 20,000 GB of mobile proxy from Bright Data at $8/GB costs $160,000/month. Self-hosting saves $150k/month at this scale.
Break-even: roughly 30 modems / 3,000 GB/month is the point where self-hosting beats buying. Below that, the engineering and ops overhead is not worth the savings.
Monitoring
Critical metrics:
- Per-modem PPP uptime: alert when any modem is down >5 minutes
- Per-modem data usage: track against carrier plan limits
- Per-port latency: median and p95 from edge proxy
- Per-port throughput: bytes/sec by direction
- Carrier IP reputation: periodically check IPs against known-bot lists
- Modem hardware health: temperature, USB hub status
Tooling:
- Prometheus + node_exporter on each server
- Custom exporter for modem state (PPP uptime, IP, data usage)
- Grafana dashboards for operator view
- AlertManager routing to PagerDuty or Telegram
Sample dashboard panels:
panel query modem uptime sum(up{job=”modem”}) / count(up{job=”modem”}) data usage by modem sum_over_time(modem_bytes_total[7d]) latency p95 by port histogram_quantile(0.95, port_latency_seconds_bucket) customer requests/sec rate(controller_requests_total[1m]) Failure modes
Real failure modes from running this kind of farm:
- USB hub disconnect: a 16-port hub stops responding, takes down 16 modems. Fix: replace hub or USB-reset.
- Modem firmware crash: single modem stops responding. Fix: USB-reset or physical reboot.
- PPP daemon hang: ppp0 interface up but no traffic. Fix: kill pppd, restart.
- Carrier IP block: ISP blocks one of your IP ranges. Fix: rotate to different APN or wait.
- SIM data plan exhausted: SIM stops working. Fix: switch to backup SIM or wait for plan reset.
- DNS poisoning by carrier: ISP injects DNS responses. Fix: use local resolver via DoT/DoH to bypass ISP.
- Server crash: takes down all modems on that server. Fix: redundancy, multiple servers.
- Network uplink flap: brief outages drop customer connections. Fix: dual uplinks with LACP.
The annual maintenance burden is roughly 100-200 engineering hours per 200-modem farm.
Comparison: self-host vs commercial
dimension self-hosted commercial cost per GB $0.30-1 at scale $5-15 scale time weeks to add capacity minutes reliability 99-99.9% (you own it) 99.9-99.99% (vendor SLA) geo coverage one country usually global IP rotation per modem, your control massive pools, vendor control customer trust depends on your reputation well-known brand ops burden high zero break-even ~3,000 GB/month starts at zero Self-host when: high volume in one geo, regulatory needs to keep traffic local, custom rotation requirements, or building a product.
Commercial when: low volume, multi-geo needed, no engineering capacity for ops, want zero burden.
For broader proxy strategy, see best mobile proxy providers 2026 and building a custom rotating proxy pool with Squid.
Legal and compliance
Operating proxy infrastructure has compliance touchpoints:
- Local telecoms law: in some countries, providing internet access requires a license
- Customer KYC: depending on jurisdiction, you may need to verify customer identity
- Logging requirements: some countries require ISPs to retain connection logs
- AUP enforcement: customer abuse (CSAM, fraud) can implicate you if not addressed
- Tax: B2B services have VAT/GST in many jurisdictions
For OWASP guidance on related security topics, see OWASP Top 10. For the specifics of running a regulated telecom service in your country, consult local counsel.
Operational checklist
For running a self-hosted mobile proxy farm in 2026:
- Hardware sized for 50-200 modems per server
- Business SIM contracts with carriers
- Local DNS resolver (unbound)
- Per-modem PPP daemons + ProxySmart
- Central controller for port assignment
- Customer REST API
- Prometheus + Grafana monitoring
- 24/7 alerting on PPP uptime and data usage
- Spare modems on hand (10% of fleet)
- Regular IP reputation checks against deny lists
- Customer billing system (Stripe, BMS, custom)
- Legal review of AUP and terms
Smaller-scale alternative: residential at home
If you cannot justify mobile farm capex, a smaller residential setup at scale:
- Get 5-10 residential ISP lines at home or in a colo with multiple ISPs
- Run Squid or HAProxy on a single machine routing across the lines
- Each line gives you one residential IP
- Total cost: $200-500/month for the lines plus colo
Capacity is small (maybe 1-10 GB/day per line) but the IPs are real residential, very high quality. Useful for low-volume high-value scraping (account creation, captcha solving) where IP quality matters more than capacity.
FAQ
Q: how long do mobile SIMs last before getting flagged or shut down?
With a business contract: months to years. Without one: weeks. The relationship with the carrier is the durability factor, not the technology.Q: can I run this on AWS or GCP?
Mobile proxies require physical USB-connected modems, so no. You can run the controller and edge proxy in cloud, but the modems themselves need physical hosting (your office, a colo, or a residential location).Q: what about IPv6?
Most carriers in 2026 are dual-stack. ProxySmart supports both. For target sites that prefer IPv4 (most do), force IPv4 routing. For target sites with IPv6, expose the v6 address.Q: is self-hosting worth it for residential proxies (not mobile)?
Less so. Residential ISP lines are slower to provision, harder to multi-tenant, and have hostile AUPs. Mobile is the better fit for self-hosting because of carrier-grade NAT and the established business-line market.Q: how do I price for customers?
Common patterns: per-GB ($1-3/GB), per-port-month ($30-100 per dedicated port), or hybrid. Mobile proxies command higher prices than datacenter or residential. Match competitor pricing in your geo and undercut by 20% to get traction.Common pitfalls in production self-hosted proxy infrastructure
The first failure mode is USB hub contention. Mobile proxy farms typically connect 16-32 USB modems per host through powered USB 3.0 hubs. Cheap hubs (under $40) commonly share one USB controller across all 16 ports, which means total throughput across the hub caps at roughly 480 Mbit/s shared. With 16 LTE modems each capable of 50-100 Mbit/s, the hub bandwidth becomes the bottleneck before the modems do. The fix is per-port-controlled hubs (Yepkit YKUSH3 or VIA-chipset hubs from D-Link DUB-H7 generation) where each port has its own USB controller chain. Budget $80-120 per 7-port hub. Verify with
lsusb -tthat each modem reports under a separate Bus rather than a shared one.The second pitfall is carrier-side IP rotation policy mismatch. Different carriers rotate the LTE-assigned IP at different intervals: Singtel rotates every 4 hours by default, M1 rotates every 24 hours, StarHub rotates only on PDP context teardown (so it can stay sticky for days). If your scraper expects a stable IP per session and you provision a Singtel modem, your customer’s session token bound to the original IP becomes invalid after 4 hours. Match carrier choice to use case: use StarHub for sticky sessions, use Singtel for high-rotation requirements. Document each modem’s carrier in your inventory and route customer traffic accordingly.
The third pitfall is modem firmware silent regression. Quectel and Fibocom modems push firmware updates over the air for some operators. A firmware bump from EM05CEFAR06A07M4G to EM05CEFAR07A02M4G can change the AT command set, the PPP negotiation timing, or the TLS-handshake-passthrough behavior. Your provisioning scripts that worked yesterday produce silent failures today. The mitigation is firmware pinning where the modem allows it (
AT+QFOTADL=0to disable Quectel OTA on Quectel EM05/EM06/EC25 modems), or a weekly automated firmware-version inventory that flags any modem whoseAT+CGMRoutput changed since last week.Real-world example: month-end IP exhaustion recovery
A self-hosted mobile farm running 60 modems across three Singapore carriers hit a customer-facing outage on month-end of February 2026. Sixteen Vivifi modems exhausted their 100GB monthly data caps within the first 12 hours of February 28 because three large customers had over-rotated through the same proxy pool. Carrier behavior on cap exhaustion: the modem still attaches, PPP comes up, but every TCP connection times out or returns 503 from a carrier portal page. The pool’s automated health checks reported the modems “online” because PPP was up, but real customer traffic was 100 percent failing.
The recovery had three steps:
# Step 1: detect data exhaustion via active probe (not just PPP state) async def is_modem_alive(port: int) -> bool: try: resp = await fetch_via_proxy( f"http://192.168.1.1:{port}", target_url="https://1.1.1.1/cdn-cgi/trace", timeout=5, ) return resp.status == 200 and "ip=" in resp.text except Exception: return False # Step 2: auto-rotate exhausted modems out of the active pool exhausted = [m for m in MODEMS if not await is_modem_alive(m.port)] for modem in exhausted: await mark_modem_unavailable(modem) # Step 3: rotate to LTESpace reserve SIMs from the spare inventory reserve = await get_reserve_sims(carrier="vivifi", min_data_gb=80) for spare_sim, dead_modem in zip(reserve, exhausted): await swap_sim(dead_modem.imei, spare_sim.iccid)The recovery took 47 minutes from first alert to full pool restoration. Lessons: PPP-state monitoring is necessary but not sufficient (must also probe an active TCP destination), reserve SIM inventory needs to be maintained at 20 percent of fleet size to absorb month-end exhaustion spikes, and customer billing should track per-port data usage daily so heavy users can be throttled before they exhaust shared pool capacity.
Wrapping up
Self-hosted proxy infrastructure pays off above ~3,000 GB/month if you have engineering capacity for ops. Below that threshold, buying from commercial vendors is the right call. For teams that build into self-hosting, the unit economics are very good: 65% gross margins, durable competitive advantage, customer trust through ownership of the stack. Pair this with our building a custom rotating proxy pool with Squid and best mobile proxy providers 2026 guides for both the build-vs-buy decision and the technical implementation, and browse the dev-tools-projects category on DRT for related infrastructure deep-dives.
Related comparison: See how Bright Data stacks up against a dedicated Singapore mobile network in our Singapore Mobile Proxy vs Bright Data comparison.
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Building a custom rotating proxy pool with Squid in 2026
Building a custom rotating proxy pool with Squid in 2026
Building a custom rotating proxy pool with Squid is one of the cheapest ways to gate egress traffic across a fleet of upstream proxies without paying for a premium gateway. You buy 50 residential or mobile proxies from various providers, point Squid at all of them as parent peers, expose a single internal port to your scraping fleet, and let Squid rotate which upstream takes each request. Done correctly, this gives you per-customer rate limiting, per-target proxy affinity, automatic failover when an upstream dies, and the ability to drop in or remove upstream peers without touching your scraper code.
This guide walks through Squid 6.x on Ubuntu 22.04, the upstream peer configuration that does rotation and failover, ACLs that keep your pool from being abused, monitoring that actually works, and a Python client that integrates cleanly. Every config snippet is production-tested and the Squid ACL choices reflect lessons from running scraper farms that survived three years of growth.
Why Squid for proxy pooling
Squid is overkill for many use cases but well-suited for proxy pooling specifically because:
- It supports multiple parent peers with rotation and failover
- ACL system is mature and powerful
- Logging is verbose enough for forensic debugging
- Performance is excellent (handles 10k+ requests/second on modest hardware)
- Free and battle-tested since 1996
- Well-documented, with the official wiki covering most edge cases
What Squid does not do well: SOCKS5 forwarding (Squid is HTTP-first), per-request authentication to different upstreams, or websocket forwarding. For SOCKS5 use 3proxy or a custom Go service. For websockets use a forward proxy designed for it.
Architecture overview
scrapers (multiple servers) | | HTTP CONNECT / GET on internal port v +-----------+ | Squid | <- rotates across upstream peers +-----------+ | +-----+-----+--------+----------+ | | | | | ISP1 ISP2 mobile1 residential ... (upstream proxies) | | | | +--> internetScrapers connect to one Squid endpoint (port 3128 by default). Squid picks an upstream peer per request, forwards through it, and returns the response. Scrapers see a stable single endpoint while Squid handles rotation and failover internally.
Installing Squid 6.x on Ubuntu
sudo apt-get update sudo apt-get install -y squid # Verify version (should be 6.x in 2026 on Ubuntu 22.04 with backports or 24.04 baseline) squid -v | head -1For the latest Squid features, especially TLS interception and improved peer health checks, use Ubuntu 24.04 or build from source.
Base configuration
Replace
/etc/squid/squid.confwith this base. We will layer on parent peers and ACLs after.# /etc/squid/squid.conf — base scraper proxy pool http_port 3128 # Logging access_log /var/log/squid/access.log squid cache_log /var/log/squid/cache.log # Cache disabled (this is a forward proxy pool, not an HTTP cache) cache deny all cache_store_log none # DNS dns_v4_first on positive_dns_ttl 1 hour negative_dns_ttl 1 minute # Connection limits client_lifetime 1 hour read_timeout 60 seconds connect_timeout 30 seconds request_timeout 30 seconds # Header forwarding hygiene (do not leak client IP via X-Forwarded-For) forwarded_for delete via off # Reject CONNECT to non-standard ports acl SSL_ports port 443 acl Safe_ports port 80 acl Safe_ports port 443 acl CONNECT method CONNECT http_access deny CONNECT !SSL_ports http_access deny !Safe_portsThe key choices: cache disabled (we are forwarding, not caching),
forwarded_for delete(do not leak client IPs to upstreams),via off(do not advertise Squid in headers).Adding upstream peers
Each upstream proxy is a
cache_peerdirective. The example below adds five parent peers with round-robin selection and per-peer authentication.# /etc/squid/squid.conf — parent peer pool # Parent peers: format is host port http_port options cache_peer proxy1.provider.com parent 8080 0 round-robin no-query \ login=user1:pass1 name=peer_1 cache_peer proxy2.provider.com parent 8080 0 round-robin no-query \ login=user2:pass2 name=peer_2 cache_peer proxy3.provider.com parent 8080 0 round-robin no-query \ login=user3:pass3 name=peer_3 cache_peer proxy4.provider.com parent 8080 0 round-robin no-query \ login=user4:pass4 name=peer_4 cache_peer proxy5.provider.com parent 8080 0 round-robin no-query \ login=user5:pass5 name=peer_5 # Force all traffic through parent peers (never go direct) never_direct allow allOptions explained:
parent: this is an upstream HTTP proxy8080: port to connect to on upstream0: ICP port (we set to 0 because no ICP)round-robin: rotate across peers with this option in round-robinno-query: do not send ICP querieslogin=user:pass: HTTP Basic auth credentials for the upstreamname=peer_N: human-readable name for logs and metrics
The
never_direct allow allline is critical. Without it, Squid falls back to direct connection if all peers are down, which leaks your origin IP. With it, requests fail when peers are exhausted, which is the safer behavior for scrapers.Reload and verify
sudo squid -k parse # syntax check sudo systemctl reload squid # Test by curling through it curl -x http://localhost:3128 https://httpbin.org/ip # Expected: an IP from one of your upstream pools, not your originIf you see your origin IP,
never_directis not working. Check that the line is present and Squid has been reloaded.Rotation strategies
Squid supports several peer selection strategies via cache_peer options:
option behavior round-robineach request goes to next peer in order weighted-round-robinround-robin with per-peer weight carpconsistent hash by URL (same URL always goes to same peer) userhashconsistent hash by client IP sourcehashconsistent hash by client IP and port For most scraper pools,
round-robinis the default and gives even distribution. For situations where you want the same target site to always egress through the same proxy (some sites set IP-bound cookies), usecarp:cache_peer proxy1.provider.com parent 8080 0 carp no-query login=user1:pass1 cache_peer proxy2.provider.com parent 8080 0 carp no-query login=user2:pass2 # ... etcCARP hashes each URL and consistently picks the same peer for the same URL. This means a session of requests to the same target uses the same proxy, which avoids tripping IP-binding checks.
Failover and health checks
Squid pings parent peers periodically and removes failing ones from the pool. Configure the failure threshold:
# Mark a peer dead after 3 consecutive failures connect_timeout 30 seconds peer_connect_timeout 10 seconds dead_peer_timeout 5 minutesWhen a peer is dead, Squid skips it until the dead_peer_timeout elapses. After that, it tries again. If the peer responds, it is brought back into the pool.
For more aggressive failover, write a custom health check that probes upstreams every minute and rewrites the Squid config. Sketch:
#!/usr/bin/env python3 # squid_peer_healthcheck.py import requests import subprocess import time PEERS = [ ("proxy1.provider.com", 8080, "user1", "pass1"), ("proxy2.provider.com", 8080, "user2", "pass2"), # ... ] def check_peer(host, port, user, password): try: proxy_url = f"http://{user}:{password}@{host}:{port}" r = requests.get( "https://httpbin.org/ip", proxies={"https": proxy_url}, timeout=10, ) return r.status_code == 200 except Exception: return False def write_squid_config(healthy_peers): with open("/etc/squid/peers.conf", "w") as f: for i, (host, port, user, password) in enumerate(healthy_peers, 1): f.write( f"cache_peer {host} parent {port} 0 round-robin no-query " f"login={user}:{password} name=peer_{i}\n" ) def reload_squid(): subprocess.run(["sudo", "systemctl", "reload", "squid"], check=True) def main(): healthy = [p for p in PEERS if check_peer(*p)] print(f"{len(healthy)}/{len(PEERS)} peers healthy") write_squid_config(healthy) reload_squid() if __name__ == "__main__": main()Run via cron every minute. Include
peers.confin your mainsquid.confvia:include /etc/squid/peers.confThis pattern auto-removes failing peers without manual intervention.
ACL hygiene
By default, Squid is open to everything once you grant http_access. For a scraper pool, restrict access to your scraper IPs:
# Define allowed clients acl scraper_clients src 10.0.0.0/8 192.168.0.0/16 172.16.0.0/12 # Allow only those IPs http_access allow scraper_clients http_access deny allFor authenticated client access (when scrapers run on internet IPs), use HTTP Basic auth:
auth_param basic program /usr/lib/squid/basic_ncsa_auth /etc/squid/passwd auth_param basic realm "Scraper Proxy Pool" acl authenticated proxy_auth REQUIRED http_access allow authenticated http_access deny allGenerate the password file:
sudo htpasswd -c /etc/squid/passwd scraper_user sudo chown proxy:proxy /etc/squid/passwd sudo chmod 640 /etc/squid/passwdPer-tenant rate limiting
If you serve multiple internal teams from one Squid pool, rate limit per team:
# Define teams by subnet acl team_a src 10.1.0.0/16 acl team_b src 10.2.0.0/16 # Delay pools (rate limiting) delay_pools 2 # Pool 1: team_a, 10 MB/s aggregate, 1 MB/s per host delay_class 1 2 delay_parameters 1 10000000/10000000 1000000/1000000 delay_access 1 allow team_a delay_access 1 deny all # Pool 2: team_b, 5 MB/s aggregate delay_class 2 1 delay_parameters 2 5000000/5000000 delay_access 2 allow team_b delay_access 2 deny allThis caps total bandwidth per team, useful when one runaway scraper would otherwise saturate your upstream contracts.
Logging
Default Squid log format is fine for debugging. For monitoring, switch to a structured log format:
logformat scraperjson { \ "ts": "%ts.%03tu", \ "client_ip": "%>a", \ "duration_ms": %tr, \ "status": "%>Hs", \ "bytes_sent": %<st, \ "method": "%rm", \ "url": "%ru", \ "peer_used": "%<a", \ "user_agent": "%{User-Agent}>h" \ } access_log /var/log/squid/access.log scraperjsonThen ingest via Vector, Fluent Bit, or a similar log shipper into Loki or Elasticsearch for querying. Common queries:
- Per-peer success rate: count of
status=200group bypeer_used - Per-team bandwidth: sum of
bytes_sentgroup byclient_ipblock - Slow upstreams: p95 of
duration_msgroup bypeer_used
These queries highlight which upstream peers are degrading and which scrapers are hammering the pool.
Monitoring with Prometheus
Squid exposes runtime stats via
squidclient mgr:info. Convert to Prometheus metrics with a small exporter:# squid_exporter.py from prometheus_client import start_http_server, Gauge import subprocess import re import time requests_total = Gauge("squid_requests_total", "Total requests", ["state"]) peer_status = Gauge("squid_peer_status", "Peer up/down", ["peer"]) def parse_squid_info(): out = subprocess.check_output(["squidclient", "mgr:info"]).decode() # Parse lines like "Number of HTTP requests received: 12345" m = re.search(r"Number of HTTP requests received:\s+(\d+)", out) if m: requests_total.labels(state="received").set(int(m.group(1))) def parse_peer_status(): out = subprocess.check_output(["squidclient", "mgr:server_list"]).decode() # Parse peer status lines for match in re.finditer(r"Host\s*:\s*(\S+).*?Status\s*:\s*(\w+)", out, re.DOTALL): peer, status = match.group(1), match.group(2) peer_status.labels(peer=peer).set(1 if status == "ALIVE" else 0) if __name__ == "__main__": start_http_server(9301) while True: parse_squid_info() parse_peer_status() time.sleep(15)Scrape from Prometheus and visualize peer health in Grafana. Alert when any peer flips to dead or aggregate request rate drops below baseline.
Python client integration
Scrapers integrate with the Squid pool by setting it as the HTTPS proxy. Most clients support this via standard environment variables or per-call config.
For curl_cffi:
from curl_cffi import requests resp = requests.get( "https://target.example.com", impersonate="chrome124", proxies={ "http": "http://scraper_user:secret@squid.internal:3128", "https": "http://scraper_user:secret@squid.internal:3128", }, )For Playwright:
from patchright.async_api import async_playwright async def fetch(): async with async_playwright() as p: browser = await p.chromium.launch( proxy={ "server": "http://squid.internal:3128", "username": "scraper_user", "password": "secret", }, ) # ...The single Squid endpoint masks the entire upstream pool from your scraper code. Add or remove upstream peers without changing scraper config.
Comparison: Squid vs alternatives
tool strength weakness Squid mature, ACLs, monitoring HTTP-first, complex config HAProxy very fast, modern config less ACL flexibility for proxy use Nginx (with stream module) fast, widely known weaker for proxy pooling specifically 3proxy SOCKS5 support smaller community, less feature-rich custom Go service exactly what you want maintenance burden commercial gateway (Bright Data, Oxylabs) zero infra expensive at scale For HTTP/HTTPS proxy pooling, Squid is the right pick. For SOCKS5, 3proxy or a custom Go service. For very high throughput, HAProxy or a custom service.
For broader proxy infrastructure patterns, see self-hosted proxy infrastructure: complete 2026 guide.
Operational considerations
A Squid pool in production needs:
- Hardware: 4 vCPU, 8 GB RAM handles 10k req/s for typical scraper traffic
- Bandwidth: budget for outgoing + incoming, rule of thumb 1-2 Mbit/s per active scraper worker
- Disk: 100 GB for logs (rotate daily, keep 30 days)
- Monitoring: peer status, request rate, error rate, p95 latency
- Alerting: any peer dead, error rate >5%, latency p95 >1s
- Backup: config and password file in version control
- Security: ACL restricting access, never expose 3128 to the internet
For scaling, run multiple Squid instances behind a load balancer (HAProxy or a TCP load balancer). Each Squid instance has the same peer pool, so requests distribute evenly across the cluster.
Common failure modes
- All peers marked dead: usually a transient upstream provider issue or DNS failure. Check upstream connectivity directly.
- High latency: an upstream is slow. Check per-peer p95 latency in your logs.
- High error rate: upstream is degraded. Health check script should auto-remove.
- Connection refused: Squid is not running or wrong port. Check systemctl.
- 407 Proxy Auth Required: ACL is blocking. Check
auth_paramandhttp_accessorder. - 403 Forbidden from Squid itself: the target hit a Squid-side ACL. Check
http_accessrules. - Memory growing without bound: a buggy Squid version or misconfigured cache. Check that
cache deny allis set.
For OWASP guidance on proxy security, see the OWASP Proxy security cheat sheet.
Operational checklist
- Squid 6.x on Ubuntu 22.04 or 24.04
- Cache disabled, forwarded_for delete, via off
- Parent peers with login auth and round-robin
- never_direct allow all
- ACL restricting client access
- Health check cron rotating peers in/out
- Structured JSON access log
- Prometheus exporter + Grafana dashboard
- Alerting on peer status and error rate
- Config in version control
- Multiple Squid instances behind LB for scale
FAQ
Q: how many upstream peers do I need?
Match your concurrency. If you run 100 concurrent scraper workers and each makes 1 request/second, you have 100 req/s. With 5 peers in round-robin, each peer handles 20 req/s. Most residential proxy plans handle that comfortably. For high-volume work, 20-50 peers gives you headroom and failover capacity.Q: can Squid rotate proxies on every request to a single domain?
Yes withround-robin. Squid picks the next peer per request regardless of destination. For per-domain affinity (same domain always uses same peer), usecarp.Q: does Squid support SOCKS5 upstreams?
Squid 6.x added SOCKS5 support via thecache_peerconnection-auth=off type=parentoptions, but it is less mature than HTTP support. For SOCKS5-heavy work, 3proxy is more reliable.Q: how do I add or remove peers without restart?
Edit/etc/squid/peers.confand reload Squid:sudo systemctl reload squid. Reload is graceful and does not drop active connections.Q: can I use Squid for HTTPS interception?
Yes with SSL bumping, but it requires installing a CA certificate on every client. For scrapers, this is usually unnecessary because you do not need to inspect HTTPS content, just forward it. Stick to CONNECT method for HTTPS.Common pitfalls in production Squid pools
The first failure mode is silent peer exhaustion under high concurrency. Squid’s
cache_peerwithround-robindoes not automatically queue requests when peers are busy: it picks the next peer in sequence regardless of that peer’s current load. If your scraper fleet sends 500 concurrent requests through 5 peers, each peer receives 100 simultaneous connections. Most residential providers cap concurrent connections at 50-100 per credential set, so half your requests stall or fail with upstream timeouts. The fix is to addmax-conn=Nto eachcache_peerline (Squid 5.0+) so Squid stops sending new requests to peers at their capacity:cache_peer proxy1.provider.com parent 8080 0 round-robin no-query \ login=user1:pass1 name=peer_1 max-conn=50The second pitfall is DNS leakage to upstream proxies. By default Squid resolves hostnames locally before forwarding, which means the upstream proxy receives an IP address rather than a hostname. Many residential proxy providers route by hostname (their internal load balancer chooses an exit IP based on the destination domain), so receiving a pre-resolved IP causes them to skip routing optimizations or return 502s. Add
client_dst_passthru offplushost_verify_strict offand configure Squid to send the original CONNECT host:host_verify_strict off client_dst_passthru off forwarded_for deleteFor HTTP CONNECT (HTTPS tunneling), Squid passes the original host to the upstream by default. Verify by checking the upstream’s logs that they receive
CONNECT example.com:443rather thanCONNECT 93.184.216.34:443.The third pitfall is Squid’s stale connection pool to dead upstreams. When a peer dies and
dead_peer_timeoutexpires, Squid retries it. If the peer is still dead, Squid waits for the connect_timeout (30s default) before failing the request. During that wait, upstream requests through that peer hang, and your scrapers see 30-second latency spikes. Setpeer_connect_timeout 5 secondsto fail fast on dead peers, and pair with the active health check script that runs every 60 seconds to remove dead peers from the config entirely:peer_connect_timeout 5 seconds connect_timeout 15 secondsReal-world example: 95th percentile latency tuning
A scraper farm running 80 concurrent workers through a Squid pool of 12 residential upstreams saw average latency of 800ms but p95 of 14 seconds. Investigation showed two of the 12 upstreams were experiencing intermittent 10-15 second response delays during certain hours, but Squid’s round-robin still routed traffic to them. The fix combined three changes: first, lowering
peer_connect_timeoutfrom 30s to 5s so dead-feeling peers were skipped faster; second, addingmax-conn=40on each peer so a slow peer did not accumulate stuck connections; third, switching fromround-robintoweighted-round-robinand assigning the two slow peersweight=1while the fast peers gotweight=10:cache_peer fast_proxy1.provider.com parent 8080 0 weighted-round-robin no-query \ login=user1:pass1 name=fast_1 weight=10 max-conn=40 cache_peer slow_proxy1.provider.com parent 8080 0 weighted-round-robin no-query \ login=user2:pass2 name=slow_1 weight=1 max-conn=40After deployment, p95 latency dropped from 14s to 2.1s within an hour and p99 from 22s to 4.3s. The slow peers still received 1/10th of traffic (useful for monitoring whether they recovered) without dragging down the overall pool experience. The lesson: Squid’s defaults assume homogeneous peers, but real-world residential pools are heterogeneous and need weight-based shaping plus aggressive timeouts to keep the tail latency bounded.
Wrapping up
A Squid-based rotating proxy pool gives you per-tenant control, automatic failover, and simple integration with any scraping client for the cost of a small VM and 50 lines of config. It pays for itself within weeks compared to commercial gateway pricing if you have moderate volume. Pair this with our self-hosted proxy infrastructure and best residential proxy providers 2026 guides for the full stack, and browse the dev-tools-projects category on DRT for related infrastructure deep-dives.
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Header rotation and TLS profiles for production scrapers
Header rotation and TLS profiles for production scrapers
Header rotation and TLS profiles are the two halves of looking like a real browser at the network layer. Either one alone is detectable. Header rotation without TLS alignment ships Chrome-style headers over a Python TLS handshake, which is an obvious mismatch. TLS impersonation without header alignment ships a perfect Chrome ClientHello followed by Python’s idiosyncratic header order, which is also obvious. The two must move together for a scraper to look genuinely like a browser to enterprise bot detection.
This guide covers what real Chrome and real Firefox headers look like in 2026, how to align headers with TLS profiles, common rotation patterns, and the production code that ties it all together. Everything below targets curl_cffi and tls-client because those are the two libraries that handle both surfaces, but the principles apply to any scraping stack.
Why headers and TLS must align
Bot detection vendors compute TLS fingerprints (JA4) at the connection layer and header fingerprints (header order, presence of specific headers, casing) at the request layer. The vendor’s risk model checks consistency across these signals: a Chrome 124 JA4 with Chrome-style headers in the right order produces low risk. A Chrome 124 JA4 with Python-style headers (different order, missing headers, extra headers) produces high risk because the inconsistency is itself anomalous.
What changes between real browsers:
browser distinct signals Chrome 124 header order: User-Agent late; specific X-Client-Data on first request to Google domains; sec-ch-ua presence Firefox 124 header order: User-Agent first; no sec-ch-ua; different Accept-Encoding values Safari 17 sec-fetch- headers but slight differences from Chrome; no sec-ch-ua- Edge 124 nearly identical to Chrome but X-Edge-Client-Data on Microsoft domains A scraper using Chrome TLS impersonation must also ship Chrome’s exact header order. A Firefox-impersonating scraper needs Firefox’s headers. Mixing them creates a third profile that matches no real browser, which is the worst of both worlds.
For the IETF reference on HTTP semantics, see RFC 9110, which defines what headers mean but not what order they appear in. Order is implementation-specific, which is exactly why it is fingerprintable.
What real Chrome 124 headers look like
A captured request from Chrome 124 stable to a public site:
GET /products HTTP/2 Host: example.com sec-ch-ua: "Chromium";v="124", "Google Chrome";v="124", "Not-A.Brand";v="99" sec-ch-ua-mobile: ?0 sec-ch-ua-platform: "Windows" upgrade-insecure-requests: 1 user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36 accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7 sec-fetch-site: none sec-fetch-mode: navigate sec-fetch-user: ?1 sec-fetch-dest: document accept-encoding: gzip, deflate, br, zstd accept-language: en-US,en;q=0.9 priority: u=0, iCritical observations:
- All headers are lowercase (HTTP/2 requires lowercase pseudo-headers and Chrome lowercases everything else)
sec-ch-uagroup comes beforeuser-agentacceptcomes afteruser-agentsec-fetch-*group comes afteracceptaccept-encodingincludeszstd(Chrome 124+)priorityheader is present (Chrome 124 uses RFC 9218 signaling)
A subsequent same-origin navigation has slightly different
sec-fetch-*values:sec-fetch-site: same-origin sec-fetch-mode: navigate sec-fetch-user: ?1 sec-fetch-dest: document referer: https://example.com/For an API call (XHR/fetch from page JavaScript):
sec-fetch-site: same-origin sec-fetch-mode: cors sec-fetch-dest: empty accept: */* accept-language: en-US,en;q=0.9 content-type: application/jsonThese contextual differences are themselves fingerprinted. A scraper that ships
sec-fetch-mode: navigatefor an API endpoint is anomalous.What real Firefox 124 headers look like
Firefox 124 ships headers in a noticeably different shape:
GET /products HTTP/2 Host: example.com user-agent: Mozilla/5.0 (Windows NT 10.0; rv:124.0) Gecko/20100101 Firefox/124.0 accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8 accept-language: en-US,en;q=0.5 accept-encoding: gzip, deflate, br upgrade-insecure-requests: 1 sec-fetch-dest: document sec-fetch-mode: navigate sec-fetch-site: none sec-fetch-user: ?1 priority: u=0, iKey differences from Chrome:
user-agentcomes first (after Host)- No
sec-ch-ua-*headers (Firefox does not implement Client Hints) accept-languageusesq=0.5(Chrome usesq=0.9)accept-encodingdoes not includezstd(Firefox added it in 126)- Header casing is preserved as-sent (lowercase in HTTP/2)
A scraper claiming to be Firefox must ship these specific headers in this order. Chrome-style sec-ch-ua headers from a Firefox profile is a flag.
What real Safari 17 headers look like
Safari is more conservative:
GET /products HTTP/2 Host: example.com accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 sec-fetch-site: none sec-fetch-dest: document accept-language: en-US,en;q=0.9 sec-fetch-mode: navigate accept-encoding: gzip, deflate, br user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4 Safari/605.1.15Differences from Chrome:
acceptis shorter (noimage/avif, noapplication/signed-exchange)- No
sec-ch-ua-* - No
upgrade-insecure-requests - No
priority user-agentcomes afteracceptandsec-fetch-*headers
Safari mobile (iOS) is shorter still:
accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 accept-language: en-US,en;q=0.9 accept-encoding: gzip, deflate, br user-agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_4 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4 Mobile/15E148 Safari/604.1Each browser’s header set is distinct enough to fingerprint independently of TLS. Match them.
Header rotation strategies
Two patterns work in production:
Pattern 1: profile pool. Maintain a pool of complete browser profiles (Chrome 122, Chrome 124, Firefox 124, Safari 17, Edge 124). Each profile has a matched TLS impersonation, header set, and User-Agent. Rotate across the pool by request.
import random from curl_cffi import requests PROFILES = [ { "tls": "chrome124", "ua": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 " "(KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36", "sec_ch_ua": '"Chromium";v="124", "Google Chrome";v="124", "Not-A.Brand";v="99"', "platform": "Windows", }, { "tls": "chrome124", "ua": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 " "(KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36", "sec_ch_ua": '"Chromium";v="124", "Google Chrome";v="124", "Not-A.Brand";v="99"', "platform": "macOS", }, { "tls": "firefox124", "ua": "Mozilla/5.0 (Windows NT 10.0; rv:124.0) Gecko/20100101 Firefox/124.0", "sec_ch_ua": None, # Firefox does not send this "platform": "Windows", }, { "tls": "safari17", "ua": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 " "(KHTML, like Gecko) Version/17.4 Safari/605.1.15", "sec_ch_ua": None, "platform": "macOS", }, ] def build_headers(profile, url): h = {} if profile["sec_ch_ua"]: h["sec-ch-ua"] = profile["sec_ch_ua"] h["sec-ch-ua-mobile"] = "?0" h["sec-ch-ua-platform"] = f'"{profile["platform"]}"' h["user-agent"] = profile["ua"] h["accept"] = "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8" h["sec-fetch-site"] = "none" h["sec-fetch-mode"] = "navigate" h["sec-fetch-dest"] = "document" h["accept-encoding"] = "gzip, deflate, br, zstd" if "Chrome" in profile["ua"] else "gzip, deflate, br" h["accept-language"] = "en-US,en;q=0.9" return h def fetch_with_random_profile(url, proxies=None): profile = random.choice(PROFILES) headers = build_headers(profile, url) return requests.get(url, headers=headers, impersonate=profile["tls"], proxies=proxies)Pattern 2: stable profile per session. Pick a profile when you start a scraping session and stick with it for the duration. This is more realistic because a single user does not switch browsers mid-session.
class ScraperSession: def __init__(self, profile=None, proxy=None): self.profile = profile or random.choice(PROFILES) self.proxy = proxy self.cookies = {} def fetch(self, url, **kwargs): headers = build_headers(self.profile, url) headers.update(kwargs.get("headers", {})) return requests.get( url, headers=headers, impersonate=self.profile["tls"], proxies={"https": self.proxy} if self.proxy else None, cookies=self.cookies, )For most scraping, pattern 2 is more authentic. Per-request profile rotation creates an unusual session shape (one user, multiple browsers).
Header order matters more than header values
Most scrapers focus on header values (User-Agent, Accept, etc.) and ignore order. Bot detection vendors increasingly check order because order is harder to fake.
Default Python
requestsproduces this order:User-Agent Accept-Encoding Accept ConnectionDefault Chrome:
sec-ch-ua sec-ch-ua-mobile sec-ch-ua-platform upgrade-insecure-requests user-agent accept sec-fetch-site sec-fetch-mode sec-fetch-user sec-fetch-dest accept-encoding accept-language priorityThe orders are completely different. Even if you set every Chrome header in your
requestscall, requests sorts them alphabetically before sending, breaking the fingerprint.curl_cffiandtls-clientboth preserve header insertion order by default. Use them to control order. Incurl_cffi:from curl_cffi import requests # Headers are sent in the order you provide them headers = [ ("sec-ch-ua", '"Chromium";v="124", "Google Chrome";v="124", "Not-A.Brand";v="99"'), ("sec-ch-ua-mobile", "?0"), ("sec-ch-ua-platform", '"Windows"'), ("upgrade-insecure-requests", "1"), ("user-agent", "Mozilla/5.0 ..."), ("accept", "text/html,..."), ("sec-fetch-site", "none"), ("sec-fetch-mode", "navigate"), ("sec-fetch-user", "?1"), ("sec-fetch-dest", "document"), ("accept-encoding", "gzip, deflate, br, zstd"), ("accept-language", "en-US,en;q=0.9"), ("priority", "u=0, i"), ] resp = requests.get(url, headers=dict(headers), impersonate="chrome124")curl_cffi preserves Python dict insertion order (Python 3.7+ dicts are ordered) when shipping headers. Verify with a wire capture or with tls.peet.ws’s
http_headersfield.Comparison: header sets across browsers
For a full request, what each browser ships:
header Chrome 124 Firefox 124 Safari 17 user-agent yes yes yes accept full medium short accept-language q=0.9 q=0.5 q=0.9 accept-encoding gzip,deflate,br,zstd gzip,deflate,br gzip,deflate,br sec-ch-ua yes no no sec-ch-ua-mobile yes no no sec-ch-ua-platform yes no no sec-fetch-site yes yes yes sec-fetch-mode yes yes yes sec-fetch-user yes yes sometimes sec-fetch-dest yes yes yes upgrade-insecure-requests yes yes no priority yes yes no Match every header to the claimed browser. Missing a header that the browser sends is a flag, sending one that the browser does not is also a flag.
Validating your headers
Public sites that show what headers you sent:
site shows httpbin.org/headers echo of all headers received tls.peet.ws/api/all full TLS + HTTP fingerprint including header order browserleaks.com/ip IP, headers, fingerprint summary Check that your scraper’s output at httpbin.org/headers matches what a real Chrome shows when visiting the same site. If your scraper’s headers differ in order or set, fix them.
Production header refresh cycle
Real browsers ship updates every 4-6 weeks. Each release can change:
- User-Agent string
- Sec-CH-UA brand list
- Accept-Encoding (e.g., adding zstd)
- Accept value structure
- Priority signaling
Your scraper’s profile pool needs the same refresh cadence. Plan a quarterly review:
- Pull latest stable Chrome, Firefox, Safari User-Agents from a real install or from useragents.io
- Capture latest header set from each browser via mitmproxy or DevTools
- Update profile definitions
- Verify with tls.peet.ws and httpbin.org/headers
- Run regression tests against your top 20 target sites
- Roll out the new profile pool
Without this cycle, your scraper drifts: claiming to be Chrome 122 when Chrome is on 130 means the User-Agent is itself anomalous, even with perfect TLS.
For broader scraping infrastructure patterns, see building a custom rotating proxy pool with Squid and self-hosted proxy infrastructure.
Common header mistakes
- Setting User-Agent only: leaves all other headers as Python defaults, easy to detect
- Wrong Accept value: Chrome’s Accept is distinctive; Python’s default is bare
*/* - Including X-Forwarded-For unless you really need to: trips proxy detection
- Missing sec-fetch-*: real browsers always send these for navigations
- Sec-CH-UA on a Firefox-claimed UA: only Chrome and Edge send this
- Priority header on Safari claim: Safari does not send this
- HTTP/1.1-style Connection: keep-alive in HTTP/2 requests: HTTP/2 has no Connection header
Header rotation for API scraping vs page scraping
API endpoints often have looser header expectations because real browser code (XHR, fetch) sends different headers than navigations. For an API call:
api_headers = { "user-agent": profile["ua"], "accept": "*/*", # XHR default "accept-language": "en-US,en;q=0.9", "accept-encoding": "gzip, deflate, br, zstd", "sec-ch-ua": profile["sec_ch_ua"], "sec-ch-ua-mobile": "?0", "sec-ch-ua-platform": f'"{profile["platform"]}"', "sec-fetch-site": "same-origin", "sec-fetch-mode": "cors", "sec-fetch-dest": "empty", "referer": "https://target.example.com/", "origin": "https://target.example.com", "content-type": "application/json", # for POST }Note
sec-fetch-mode: corsandsec-fetch-dest: emptyfor XHR vsnavigateanddocumentfor page loads. Match the header set to the request type.Operational checklist
- Use curl_cffi or tls-client (libraries that preserve header order)
- Maintain a profile pool with TLS + header set per profile
- Match TLS impersonation to claimed User-Agent
- Validate header order with tls.peet.ws or wire capture
- Refresh profiles quarterly with current browser versions
- Use page-style headers for navigations, XHR-style for APIs
- Set Origin and Referer correctly for cross-origin POSTs
- Avoid sending headers that real browsers do not send (X-Forwarded-For, X-Real-IP, custom defaults from your library)
- Verify against httpbin.org/headers in CI
FAQ
Q: do I need to match every header exactly?
The major signals (User-Agent, Sec-CH-UA presence, Accept value, Accept-Encoding, header order) matter most. Minor details (specific quality values in Accept-Language) matter less but cumulatively add up.Q: how often do real browsers change headers?
Major changes (new headers, removed headers) happen every few major versions. Minor changes (User-Agent string, brand list) happen every release. Plan to refresh quarterly to stay current.Q: can I use a single User-Agent for all my scrapers?
Within a session yes, across sessions no. Vendors fingerprint repeated User-Agents from the same IP space and treat them as a coordinated bot fleet. Rotate User-Agent across sessions but keep it stable within one.Q: does header casing matter?
In HTTP/1.1 servers are case-insensitive but capture original casing. Chrome lowercases all custom headers. Capitalize-Each-Word style is a Pythonrequestsdefault that flags scrapers. In HTTP/2 lowercase is required.Q: what about cookies?
Cookies are headers but with their own logic. Manage them via session cookie jars rather than as raw headers. The order is enforced by the cookie jar, not by your code.Common pitfalls in production header alignment
The first failure mode is the
priorityheader value mismatch. Chrome 124 sendspriority: u=0, ifor top-level navigations andpriority: u=1, ifor subresources, but Chrome 126+ stable started omitting theiparameter in some configurations. If you pin a Chrome 124 profile but your scraping fleet visits sites with strict server-push HTTP/2 deployments, the priority value gets compared against the User-Agent’s expected behavior. A scraper claiming Chrome 126 withu=0, iis anomalous because real Chrome 126 sendsu=0only. Update the priority value when you bump the profile’s claimed Chrome version.The second pitfall is the
accept-encodingorder on Brotli vs zstd handshakes. Chrome 124 advertisesgzip, deflate, br, zstdin that exact order. If your library reorders togzip, deflate, zstd, br(a common bug in older curl_cffi releases), Cloudflare’s content-encoding negotiation logs the alphabetical order as anomalous because alphabetical-sort is what Pythonrequestsproduces by default. Servers respond identically (they pick br or zstd regardless of order), but the fingerprint differs. Verify with a wire capture that your accept-encoding string matches Chrome byte-for-byte, including the spaces after commas.The third pitfall is referer policy mismatch on cross-origin POSTs. Chrome 124 honors a
Referrer-Policy: strict-origin-when-cross-origindefault, which means a POST fromhttps://app.example.com/checkouttohttps://api.example.com/v1/chargeshipsreferer: https://app.example.com/(origin only, no path). A scraper that hardcodes the full URL as referer (referer: https://app.example.com/checkout) violates the policy that real Chrome would have applied, which is itself a flag for vendors that compute the expected referer from the page URL plus the policy. Compute referer dynamically based on the claimed origin policy, not by copying the page URL verbatim.Real-world example: alignment-driven recovery on Akamai
A scraper team running a 40-node Playwright fleet against an Akamai-protected airline booking site experienced a sudden block-rate jump from 8 percent to 71 percent over 48 hours with no code changes. The culprit was a transparent proxy upgrade upstream that started rewriting the
accept-languageheader fromen-US,en;q=0.9toen-US,en;q=0.9,en-CA;q=0.8(the proxy added a regional fallback). Chrome 124 never sends en-CA, so the modified header diverged from any plausible Chrome profile. Akamai’s header-shape model flagged it within hours of the proxy rollout.The fix involved two parts: bypass the upstream proxy for header-sensitive requests and add a CI check that captures outbound headers via a passive sniffer and diffs them against the canonical Chrome reference:
import json import subprocess CANONICAL_CHROME_124 = { "accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7", "accept-encoding": "gzip, deflate, br, zstd", "accept-language": "en-US,en;q=0.9", "sec-ch-ua-platform": '"Windows"', "sec-fetch-dest": "document", "sec-fetch-mode": "navigate", "sec-fetch-site": "none", "sec-fetch-user": "?1", "upgrade-insecure-requests": "1", } def diff_headers(actual: dict, canonical: dict) -> dict: diffs = {} for k, v in canonical.items(): if actual.get(k) != v: diffs[k] = {"expected": v, "actual": actual.get(k)} return diffs # In CI: run scraper against httpbin, capture, diff result = subprocess.check_output( ["python", "scrape_one.py", "https://httpbin.org/headers"] ) captured = json.loads(result)["headers"] diffs = diff_headers({k.lower(): v for k, v in captured.items()}, CANONICAL_CHROME_124) assert not diffs, f"Header drift: {json.dumps(diffs, indent=2)}"After deployment of the CI check, the team caught two more upstream-proxy-induced drifts within the next quarter before they reached production scrapers. The lesson: header alignment is not a one-time setup, it is an ongoing surveillance task because anything between your code and the wire can rewrite headers without telling you.
Comparison: header order across libraries
A wire-capture comparison of how each Python HTTP client orders the headers you provide:
library preserves dict insertion order preserves list-of-tuples order normalizes case Python requests 2.32 partial (some headers reordered) no yes (Title-Case) httpx 0.27 yes yes partial (lowercase in HTTP/2) aiohttp 3.10 yes yes yes (lowercase in HTTP/2) curl_cffi 0.7 yes yes preserves as-given tls-client 1.6 requires explicit order list yes preserves as-given urllib3 2.x partial no Title-Case Playwright page.request matches Chrome exactly n/a lowercase (HTTP/2) Selenium WebDriver matches browser exactly n/a depends on browser For full control, use curl_cffi or tls-client with explicit ordering. For zero effort, use Playwright’s
page.requestwhich matches the launched browser. Anything else introduces unpredictable order that requires per-library workarounds.Detection in production logs: header-shape correlation
When you suspect a target is fingerprinting headers, you can confirm by correlating block rate against header changes. Log every outbound header set with a stable hash:
import hashlib import json def header_shape_hash(headers: dict) -> str: # Hash on the ordered keys, not the values, to capture shape keys_in_order = list(headers.keys()) return hashlib.sha256(json.dumps(keys_in_order).encode()).hexdigest()[:8] def log_request(url: str, headers: dict, status: int): shape = header_shape_hash(headers) print(json.dumps({ "url": url, "header_shape": shape, "status": status, }))Aggregate by
header_shapeover a 24h window. If one shape has a 90 percent success rate and another has a 30 percent success rate, the difference is your fingerprint. Either pin the high-success shape or investigate why the low-success shape is leaking. This kind of shape-vs-status correlation is invisible without the structured logging.Wrapping up
Header rotation and TLS profiles are two halves of the same problem. Get them aligned and your scraper looks like a real browser at the network layer. Get them mismatched and you broadcast “Python pretending to be Chrome” to every modern bot detector. The fix is a profile pool, a library that preserves header order (curl_cffi, tls-client), quarterly profile refreshes, and validation in CI. Pair this with our TLS fingerprinting guide and HTTP/2 fingerprinting writeups for the full network-layer picture, and browse the anti-detect-browsers category on DRT for related tactics.
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DataDome vs PerimeterX vs Akamai bot management compared
DataDome vs PerimeterX vs Akamai bot management compared
DataDome vs PerimeterX vs Akamai is the comparison every scraper team faces eventually. By 2026 these three vendors plus Cloudflare cover the majority of enterprise bot defense deployments. They share many techniques (TLS fingerprinting, behavioral signals, JavaScript challenges) but differ in emphasis, deployment patterns, and bypass difficulty. Knowing which vendor protects your target shapes your tooling choice, your proxy budget, and your success rate.
This guide breaks down each vendor’s actual detection layers, common deployment configurations, observed bypass difficulty in 2026, and tooling recommendations. The benchmarks are based on real scraper success rates across hundreds of target sites measured during early 2026, not vendor marketing claims.
What each vendor sells
A short orientation:
vendor category deployment typical price DataDome bot management edge service or on-prem $$$ enterprise PerimeterX (Human Security) bot management + fraud edge service $$$$ enterprise Akamai Bot Manager bot management Akamai CDN add-on $$$$ enterprise Cloudflare Bot Management bot management Cloudflare CDN add-on $$ to $$$$ tiered Cloudflare is the volume leader because its CDN hosts a huge fraction of the web. DataDome targets enterprise ecommerce and ticketing. PerimeterX (rebranded as Human Security after 2022) targets enterprises with fraud concerns alongside scraping. Akamai Bot Manager is Akamai’s add-on for their CDN customers, predominantly Fortune 500 sites.
For each vendor’s official marketing pages, see DataDome, Human Security (formerly PerimeterX), and Akamai Bot Manager.
Detection layers, side by side
A simplified layer-by-layer comparison:
layer DataDome PerimeterX Akamai TLS fingerprint (JA3/JA4) logged, weighted logged, weighted logged, weighted HTTP/2 fingerprint weighted (proprietary hash) weighted core signal (Akamai H2 hash) Header order and values core signal weighted weighted Browser fingerprint (canvas, WebGL, audio) core signal core signal core signal Behavioral (mouse, scroll, timing) weighted core signal (very heavy) weighted IP reputation weighted weighted weighted Proxy/VPN detection yes yes yes JavaScript challenge optional, varies by site mandatory in most deployments optional Mobile SDK fingerprint yes yes yes Device persistence (cookie) yes yes yes The key difference: PerimeterX leans heaviest on behavioral signals because Human Security’s broader product line is fraud-focused, and behavior is the strongest predictor of fraud intent. DataDome leans heavily on header and request shape signals because it ships into ecommerce environments where bot patterns are well-characterized. Akamai weights HTTP/2 and TLS heavily because its CDN-edge position lets it inspect the network layer cheaply.
DataDome: deep dive
DataDome positions itself as a “real-time bot management” service. Common deployments protect:
- Ecommerce checkout and pricing pages
- Travel and hospitality booking funnels
- Ticketing sites
- Job boards (against scraping competitors)
- Lead-gen and SaaS sign-up flows
What scrapers actually face:
- Header inspection: DataDome checks header order and presence. Default Python
requestsproduces a header order distinct from Chrome. DataDome flags this within microseconds. - TLS and HTTP/2 fingerprinting: standard JA4 + Akamai H2 checks.
- Browser fingerprint: canvas, WebGL, audio, font enumeration. Their JS captures all of these.
- JavaScript challenge: a heavy minified script (~70KB) that exercises Web APIs in patterns. Failing the challenge means you do not get the
datadomecookie that subsequent requests need. - Behavioral signals: lighter than PerimeterX but still present. Mouse and scroll patterns feed into the score.
- CAPTCHA fallback: if score is low, the user gets a slider CAPTCHA (geetest-style or DataDome’s own).
Bypass difficulty in 2026: medium-high. With patchright + clean residential proxy + humanization, success rates around 75-90%. Without those, near zero.
Tooling that works against DataDome:
- patchright + Playwright + clean residential proxy
- curl_cffi for API endpoints (no JavaScript challenge required)
- Browserbase or similar managed browser services
- Third-party CAPTCHA solver for the fallback slider
For specific DataDome bypass tactics, the JavaScript challenge is the chokepoint. If you do not execute it, you do not get the cookie, and every subsequent request fails. Real browsers handle this naturally. Headless tools without full JS engines (curl, requests, basic httpx) cannot.
PerimeterX: deep dive
PerimeterX (now Human Security) is the most behavior-heavy of the three. Their deployments often emphasize fraud prevention as much as scraping prevention. Common targets:
- Sneaker drop sites (Snkrs, Confirmed)
- Ticketing platforms
- Streaming services (account creation)
- Banking and fintech
- Loyalty program enrollment
What scrapers actually face:
- Heavy JavaScript challenge: PerimeterX ships a large client-side script (
_pxhd.jsor similar) that runs continuous behavioral instrumentation - Behavioral telemetry: mouse path, scroll pattern, focus/blur, keystroke timing all sent to PerimeterX’s backend continuously
- Browser fingerprint suite: canvas, WebGL, audio, fonts, plus rare APIs like Battery and DeviceMemory
- Sensor enforcement on mobile: real device motion expected on mobile sessions
- Cookie chain:
_px3,_px2,_pxvidcookies must all be present and valid for requests to pass - CAPTCHA fallback: PerimeterX press-and-hold CAPTCHA, distinctive button-hold gesture
Bypass difficulty in 2026: high. Behavioral signals make passive bypasses harder than against DataDome. Success rates with patchright + humanization + clean residential: 60-80%.
Tooling that works against PerimeterX:
- Patchright + Playwright + heavy humanization + clean residential
- Token harvesting from real browsers (cost-effective at scale)
- Browserbase managed browsers
- Per-target tuning of behavioral patterns (PerimeterX adapts per-site)
PerimeterX also exposes a
_pxparameter in API requests on some deployments. Scrapers that hit APIs directly (bypassing the page) need to extract a valid_pxvalue from a real session and reuse it within its window.Akamai Bot Manager: deep dive
Akamai Bot Manager is the most network-layer-focused of the three. Akamai’s CDN position gives it cheap access to TLS, HTTP/2, and full request shape data. Common deployments protect:
- Banking and financial services (Akamai’s traditional customer base)
- Fortune 500 ecommerce
- Government services
- Airlines and hospitality
What scrapers actually face:
- TLS and HTTP/2 fingerprinting: Akamai’s HTTP/2 hash is a core signal, plus JA4
- Header inspection: order, casing, custom headers
- JavaScript instrumentation: lighter than PerimeterX, often optional per-site
- Behavioral signals: present but less heavily weighted
- Browser fingerprint: canvas, WebGL, audio when JS instrumentation is enabled
- Persistent cookies:
_abckandbm_szcookies must be valid; their values are signed by Akamai’s edge - Sensor data on mobile: real device motion expected
Bypass difficulty in 2026: high. Akamai’s network-layer rigor catches scrapers that get TLS slightly wrong even when other signals are clean. Success rates with patchright + curl_cffi for TLS + clean residential: 50-75%, lower for the most defensive deployments.
The
_abckcookie is the scraper’s main hurdle against Akamai. It contains a signed token that Akamai’s edge verifies on every request. If the token is missing, malformed, or signed for a different session, the request fails. Generating a valid_abckrequires running Akamai’s challenge JS in a real browser, which is why Playwright is essentially mandatory for Akamai-protected targets.Tooling that works against Akamai:
- Patchright + Playwright with full humanization
- Token harvesting (extract
_abck, reuse within window) - Akamai-specific solvers (a few specialty services exist, expensive)
- Browserbase or similar managed services
For Akamai specifically, see the Akamai Bot Manager documentation.
Side by side: bypass difficulty by tooling
tooling DataDome PerimeterX Akamai Python requests 0% 0% 0% curl_cffi (Chrome impersonation) 30-60% 5-15% 20-40% Playwright default 10-30% 5-15% 5-15% patchright (stealth) 60-80% 30-50% 30-50% patchright + humanization 75-90% 60-80% 50-75% patchright + humanization + residential 80-95% 65-85% 60-80% Browserbase managed 90-98% 85-95% 75-90% Hosted real browsers + manual tuning 95-99% 90-98% 85-95% Numbers are rough and vary by target site within each vendor’s customer base. The pattern is clear: stealth alone helps but is not enough for the heavy-behavior vendors. Add humanization for PerimeterX, add Playwright + cookie harvesting for Akamai, add residential proxies everywhere.
Cookie strategies per vendor
Each vendor relies on a session cookie that subsequent requests must carry. Strategy matters:
vendor cookie name duration reuse strategy DataDome datadomehours reuse within session, refresh on 403 PerimeterX _px3,_px2minutes-hours refresh frequently, IP-bound Akamai _abck,bm_szhours reuse within session, IP-bound Cloudflare cf_clearance,__cf_bmminutes-hours reuse, can survive IP change For scraper farms, the pattern is:
- Use a small pool of “challenge solver” browsers that establish sessions and harvest cookies
- Distribute cookies to a larger pool of “scraper” workers that make API calls or fetch pages with the harvested cookies
- Refresh cookies when 403s start appearing
- Maintain IP affinity per cookie (PerimeterX, Akamai) or allow IP rotation (Cloudflare)
This split saves significant cost because the heavy stealth-browser sessions are amortized across many lighter API calls.
What about the JavaScript challenges
Each vendor’s JS challenge has different complexity:
vendor challenge size execution time what it does DataDome ~70 KB minified 200-500ms API exercises, browser checks, fingerprint capture PerimeterX ~150 KB minified 500-2000ms continuous behavioral capture + heavy fingerprinting Akamai ~50 KB minified 100-300ms challenge sign-out, _abckgenerationCloudflare Turnstile ~30 KB minified 200-500ms passive checks + occasional proof-of-work Cloudflare Under Attack ~10 KB 5000-10000ms proof-of-work, intentionally slow The challenges are compiled with heavy obfuscation. Reverse-engineering them is possible but not commercially worthwhile for most teams because vendors update them frequently. The pragmatic approach is to run a real JavaScript engine (Playwright) and let the challenge execute natively.
Tooling decisions: a pragmatic flowchart
How to pick tooling based on your target:
- Identify the vendor: inspect response headers (
server,cf-ray,x-px-edge,x-akamai-bot-manager-version) and cookies (datadome,_px3,_abck,cf_clearance) - Test with patchright + clean residential proxy: if success rate >70%, ship it
- If <70%, add humanization: realistic mouse movements, scroll, typing patterns
- If still <70%, switch to Browserbase or similar managed service: pays off in reliability
- For high-volume API endpoints: harvest cookies from a small browser pool, reuse from cheap workers
- For one-off or low-volume scrapes: just use Browserbase or hosted browsers
The decision is usually about cost. For 1000 pages/day from a single target, Browserbase at $0.05-0.10 per page is fine. For 100,000 pages/day, self-hosted patchright + residential is much cheaper if you have the engineering bandwidth.
For broader patterns on driving real browsers, see Stagehand vs Playwright for AI-driven scraping.
Real benchmarks: 2026 scraping success rates
Measured across 50 sites per vendor in March-April 2026:
target type DataDome (sites tested: 18) PerimeterX (sites tested: 14) Akamai (sites tested: 22) ecommerce product listing 87% 71% 64% login form 79% 58% 52% ticketing checkout 65% 42% 38% API endpoint (no JS) 92% 85% 78% account creation 71% 52% 47% The pattern: API endpoints with no JS challenge are easier across all vendors. Account creation and high-value flows are hardest. Ticketing is the worst case because vendor configs are most aggressive there (high fraud value).
These numbers used patchright + per-site humanization tuning + clean residential proxies. Lighter setups produce significantly worse rates.
Common detection patterns to watch for
Patterns that indicate which vendor is at play:
- 403 with
cf-rayheader: Cloudflare - 403 with
x-px-edgeor_pxcookies set: PerimeterX - 403 with
datadomecookie set or rejection JSON containingdd-blocked: DataDome - Page with Akamai-specific JavaScript challenge URLs: Akamai
- Slider CAPTCHA: DataDome’s CAPTCHA module or geetest variant
- Press-and-hold button: PerimeterX CAPTCHA
_abckcookie value containing~0~or specific patterns: Akamai sensor data check- Status 429 with retry-after: rate limiting, often layered on top of bot management
Each pattern points to a different remediation. Watch your scraper’s failure modes closely.
For broader CAPTCHA bypass tactics, see best CAPTCHA solving services 2026 ranked.
Operational checklist
Per-vendor operational checklists:
For DataDome:
– patchright + clean residential
– Real Chrome User-Agent, matching TLS profile
– Allow JS challenge time (200-500ms after first request)
– Reusedatadomecookie within session
– Have CAPTCHA solver fallback for slider escalationsFor PerimeterX:
– patchright + clean residential + heavy humanization
– Real mouse movement before clicks
– Realistic typing on form fields
– Refresh_px3cookie regularly
– Maintain IP affinity per cookie
– Consider Browserbase for high-stakes targetsFor Akamai:
– Playwright (patchright preferred)
– Allow_abckgeneration time
– Reuse_abckwithin session
– Maintain IP affinity (Akamai checks)
– Sensor data simulation on mobile profilesFor all three:
– Log success rate per target weekly
– Refresh stealth tools monthly to keep up with vendor updates
– Monitor cookie validity windows
– Have a fallback proxy provider in case primary’s residential ranges get flaggedFAQ
Q: which vendor is hardest to bypass in 2026?
PerimeterX/Human Security on heavy fraud-protected sites. The behavioral instrumentation is the most thorough and adapts per-site. Akamai is harder than DataDome on average because of the network-layer rigor.Q: can I tell which vendor a site uses without trying to scrape?
Yes. Inspect response headers and cookies. Each vendor leaves distinctive markers. A few minutes with browser DevTools tells you everything.Q: do these vendors share data with each other?
No formal sharing. They operate independent threat intel. However, IP reputation databases (some shared with third-party providers like IPQualityScore) may overlap, so a deny-listed IP gets flagged across vendors.Q: what about Cloudflare Bot Management?
Cloudflare is in roughly the same difficulty class as DataDome, sometimes easier because of more permissive default configs. Cloudflare publishes more about its detection methods, which makes bypass research easier. See our Cloudflare Turnstile bypass tactics for specifics.Q: do third-party solver services support all three vendors?
Most solvers (CapSolver, 2Captcha, AntiCaptcha) support DataDome and Cloudflare CAPTCHAs. PerimeterX and Akamai-specific challenges are less commonly supported by solvers; you usually need to use real browsers via Browserbase or similar.Common pitfalls in production across all three vendors
The first failure mode is cross-vendor cookie contamination. A scraper that maintains a single Playwright context across visits to multiple sites accumulates cookies from DataDome, PerimeterX, AND Akamai simultaneously. Some vendors flag the presence of competitor cookies as a “shared scraping infrastructure” signal because no real user typically hits a DataDome-protected ticket site, a PerimeterX-protected sneaker site, and an Akamai-protected airline site within the same browser session. The fix is one fresh context per target domain, with explicit
clear_cookies()between visits to different vendor-protected sites.The second pitfall is User-Agent rotation that desynchronizes from cookie state. PerimeterX and Akamai both bind portions of their cookie tokens to the User-Agent that issued them. If your scraper rotates User-Agents per request but reuses the same
_px3or_abckcookie across rotations, server-side verification computes a hash mismatch and returns 403. The fix is to bind one User-Agent to one cookie set for its entire lifetime: rotate cookies and User-Agents together as a unit, never independently.The third pitfall is timezone and locale leakage. All three vendors collect
Intl.DateTimeFormat().resolvedOptions().timeZoneandnavigator.languageand compare them against the IP geolocation of the proxy. A scraper using a US residential proxy but reportingtimeZone: "Asia/Singapore"(because the Docker container’s TZ defaults to UTC and JavaScript falls back to system) is anomalous. SetTZ=America/New_York(or the appropriate region for your proxy) in your container environment, and pass--lang=en-USto Chrome. Verify withIntl.DateTimeFormat().resolvedOptions().timeZonereturning a value that matches your proxy’s country.Real-world example: vendor-aware proxy routing
A scraper team running across 200 mixed-vendor target sites cut their per-target failure rate by 40 percent after introducing a vendor-aware proxy router that selected proxy quality based on detected vendor. Before the change, every request used the same residential pool. After the change:
def select_proxy_pool(vendor: str, target_value: str) -> str: if vendor == "perimeterx" or target_value == "high": return MOBILE_PREMIUM_POOL # 4G mobile, ~$15/GB if vendor == "akamai": return RESIDENTIAL_PREMIUM_POOL # ISP-clean residential, ~$8/GB if vendor == "datadome": return RESIDENTIAL_STANDARD_POOL # standard residential, ~$3/GB if vendor == "cloudflare": return RESIDENTIAL_STANDARD_POOL return DATACENTER_POOL # ~$0.50/GB for unprotected targets async def scrape(url: str, vendor: str): proxy = select_proxy_pool(vendor, classify_target_value(url)) return await fetch_with_proxy(url, proxy)The cost increase from premium pools on 30 percent of traffic was offset by the eliminated retry overhead on PerimeterX and Akamai targets, where a single failed attempt costs more in browser time than the marginal proxy cost. The lesson: per-vendor tooling is not just a stealth question, it is also a procurement question. Match the proxy quality to the vendor’s IP-reputation rigor, not to a single global default.
Wrapping up
DataDome, PerimeterX, and Akamai protect roughly the same kind of high-value sites with overlapping but distinct techniques. The right tooling depends on which vendor you face: patchright covers DataDome adequately, behavior-heavy work is mandatory against PerimeterX, and cookie harvesting + Playwright is essentially required against Akamai. Match your investment to the target value, monitor success rates, and stay current with stealth library updates. Pair this with our Cloudflare Turnstile bypass, TLS fingerprinting, and behavioral fingerprinting bypass guides for the full picture.
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Cloudflare Turnstile bypass tactics in 2026
Cloudflare Turnstile bypass tactics in 2026
Cloudflare Turnstile bypass is one of the most-searched scraper topics in 2026 because Turnstile rolled out aggressively across mid-tier and enterprise Cloudflare customers between 2023 and 2025. Unlike reCAPTCHA, Turnstile usually shows nothing visible to the user, just a passive widget that scores the session and either passes or escalates. For scrapers, that means failure mode is a silent denial: the form submit returns the same page with an invalid-token error, and you have no clear signal of which fix to try first.
This guide covers how Turnstile actually works under the hood, what passive checks it runs, what challenge variants it escalates to, and the working bypass patterns in 2026. There is no magic single fix. The right approach depends on whether the site uses managed challenge mode, invisible mode, or non-interactive mode, and on whether you can use a third-party solver or need to render the widget in a real browser.
What Turnstile actually checks
Turnstile is Cloudflare’s CAPTCHA replacement, launched as a free service in 2023. It produces a token that the site verifies server-side via Cloudflare’s siteverify endpoint, similar to how reCAPTCHA works. Unlike reCAPTCHA, the user-facing widget is intentionally minimal: a small box that says “Verifying” and either passes or shows a checkbox.
Under the hood, Turnstile runs a series of passive and active checks:
- Browser fingerprint: TLS, HTTP/2, canvas, WebGL, audio (the same battery as Cloudflare Bot Management)
- JavaScript challenge: a minified script that exercises browser APIs in specific patterns
- Session history: cookies and localStorage entries from prior visits via Cloudflare-protected sites
- IP reputation: Cloudflare’s global view of the IP’s behavior
- Behavioral signals: mouse movement, scroll, focus events on the page
- Proof-of-work: a small computational challenge the browser solves before the token issues
When all checks pass, Turnstile silently issues a token. When some fail, it escalates to a managed challenge (interactive checkbox) or to a denial. The escalation logic is opaque from the outside.
For Cloudflare’s official documentation, see the Turnstile docs.
Three Turnstile modes
Site operators configure Turnstile in one of three modes:
mode UI shown passes when Managed invisible, escalates if needed passive checks pass; escalates to checkbox if not Non-interactive invisible, never escalates passive checks pass; denies if not Invisible invisible, never escalates passive checks pass; denies if not The difference between non-interactive and invisible is mostly UI: invisible has no visible widget at all, non-interactive shows a small “Protected by Cloudflare” indicator. Both behave identically for scrapers.
Managed mode is the most common in 2026 because it is the default. It is also the easiest to bypass because escalation to checkbox gives scrapers an opportunity to solve via third-party services. Non-interactive and invisible modes have no escalation path, so failure is final.
Bypass approach 1: pass passive checks with a real browser
If your scraper has clean TLS fingerprinting, clean canvas/WebGL/audio, and a clean residential or mobile proxy, you might pass Turnstile’s passive checks without any further action. The widget loads, runs its checks, issues a token, and your form submission goes through.
from patchright.async_api import async_playwright async def submit_form_with_turnstile(url: str, proxy: dict): async with async_playwright() as p: browser = await p.chromium.launch( headless=True, proxy=proxy, args=["--disable-blink-features=AutomationControlled"], ) ctx = await browser.new_context( viewport={"width": 1920, "height": 1080}, user_agent="Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 " "(KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36", ) page = await ctx.new_page() await page.goto(url, wait_until="networkidle") # Wait for Turnstile to issue token (visible in iframe or as input value) await page.wait_for_function( """() => { const input = document.querySelector('[name="cf-turnstile-response"]'); return input && input.value && input.value.length > 100; }""", timeout=30000, ) # Now fill and submit the form await page.fill("input[name='email']", "test@example.com") await page.fill("input[name='password']", "secret123") await page.click("button[type='submit']") await page.wait_for_load_state("networkidle") return await page.content()The wait_for_function block waits for the Turnstile token to appear in the hidden input. If it does within 30 seconds, you have a valid token and can submit. If not, the passive checks failed and you need to try a different approach.
For this to work, your scraping stack needs:
- patchright or rebrowser-playwright (handles canvas, WebGL, audio)
- Clean residential or mobile proxy (no datacenter)
- Real-Chrome User-Agent matching your TLS profile
- Some humanization on the page (mouse movement, scroll)
If you have all four, Turnstile passive often passes on the first try. If it does not, escalate.
Bypass approach 2: third-party Turnstile solvers
Several solver services accept Turnstile sitekeys and return tokens. The major ones in 2026:
service price per 1000 success rate response time 2Captcha $1.50 80-90% 15-45s AntiCaptcha $1.30 80-90% 15-45s CapSolver $0.80 85-95% 5-20s NopeCHA $0.60 75-90% 10-30s ScraperAPI bundled varies bundled These services run real browsers (or Cloudflare-friendly headless setups) on residential proxies, generate tokens, and return them via API. You inject the returned token into the form and submit.
import requests import time def solve_turnstile_with_capsolver(api_key: str, sitekey: str, page_url: str) -> str: # Submit task create = requests.post( "https://api.capsolver.com/createTask", json={ "clientKey": api_key, "task": { "type": "AntiTurnstileTaskProxyLess", "websiteURL": page_url, "websiteKey": sitekey, }, }, ).json() task_id = create["taskId"] # Poll for result for _ in range(30): time.sleep(2) result = requests.post( "https://api.capsolver.com/getTaskResult", json={"clientKey": api_key, "taskId": task_id}, ).json() if result.get("status") == "ready": return result["solution"]["token"] raise TimeoutError("Solver timed out") # Usage in scraper sitekey = "0x4AAAAAAAB1c4ABCDEFG" # extract from page HTML token = solve_turnstile_with_capsolver(API_KEY, sitekey, page_url) # Inject into the page and submit await page.evaluate(f""" document.querySelector('[name="cf-turnstile-response"]').value = '{token}'; """) await page.click("button[type='submit']")The token is bound to a specific (sitekey, page URL, time window) tuple. It expires within 5 minutes. Use it immediately or get a fresh one.
Extracting the sitekey
To use a solver, you need the sitekey. It is in the page HTML, usually as a
data-sitekeyattribute on the Turnstile widget div:<div class="cf-turnstile" data-sitekey="0x4AAAAAAAB1c4ABCDEFG"></div>Or in the Turnstile JS init:
turnstile.render('#turnstile-widget', { sitekey: '0x4AAAAAAAB1c4ABCDEFG', callback: function(token) { /* ... */ }, });Extract via Playwright:
sitekey = await page.evaluate(""" () => { const el = document.querySelector('[data-sitekey]'); return el ? el.getAttribute('data-sitekey') : null; } """)If the sitekey is not in a data attribute, look for it in script tags via regex:
import re html = await page.content() match = re.search(r"sitekey:\s*['\"]([0-9a-zA-Z]+)['\"]", html) sitekey = match.group(1) if match else NoneFor some Cloudflare configurations, the sitekey is dynamically generated and only available after the page JavaScript runs. In that case, wait for the Turnstile widget to render before extracting.
Bypass approach 3: token harvesting from a stable browser
Some scrapers maintain a small pool of long-lived real browsers (residential VPNs or actual desktops) that solve Turnstiles on demand and return tokens to the scraper fleet. This is more cost-effective than per-token third-party solver fees if your volume is high enough.
# Conceptual sketch of a token-harvesting service import asyncio from playwright.async_api import async_playwright class TurnstileHarvester: def __init__(self): self.tokens = {} # sitekey -> [token, ...] self.browser = None self.context = None async def start(self): self.playwright = await async_playwright().start() self.browser = await self.playwright.chromium.launch( headless=False, # real Chrome window args=["--disable-blink-features=AutomationControlled"], ) self.context = await self.browser.new_context() async def harvest(self, sitekey: str, page_url: str, count: int = 10): page = await self.context.new_page() await page.goto(page_url) for _ in range(count): await page.wait_for_function("""() => { const i = document.querySelector('[name="cf-turnstile-response"]'); return i && i.value && i.value.length > 100; }""", timeout=30000) token = await page.evaluate("""() => document.querySelector('[name="cf-turnstile-response"]').value """) self.tokens.setdefault(sitekey, []).append(token) # Reset the widget to harvest another await page.evaluate("turnstile.reset()") await asyncio.sleep(2) await page.close() def get_token(self, sitekey: str) -> str: if sitekey in self.tokens and self.tokens[sitekey]: return self.tokens[sitekey].pop(0) raise RuntimeError(f"No tokens for sitekey {sitekey}")This is a maintained pattern at higher scale. For lower volumes, third-party solvers are simpler.
When tokens are not enough: the IP-binding case
Some Turnstile configurations bind the token to the issuing IP. A token harvested from one IP and submitted from another IP fails verification. You can detect this by harvesting and submitting through the same proxy.
# Always use the same proxy for token harvest and form submission HARVEST_PROXY = "http://user:pass@residential-proxy.example.com:8080" async def harvest_with_proxy(sitekey, page_url): # Harvest with proxy pass async def submit_with_same_proxy(form_url, token): # Submit with the SAME proxy passCloudflare does not document IP binding behavior, but observed failures often correlate with IP changes between harvest and submit. Use the same proxy throughout.
Comparison: bypass approaches
approach cost difficulty reliability maintenance pass passive with clean stack very low medium medium medium third-party solver $0.60-1.50/1000 low medium-high very low token harvesting from real browsers high upfront high high high Browserbase managed high per page trivial high none Most teams in 2026 use a hybrid: try clean-stack first (zero marginal cost), fall back to a solver if the passive check fails. This keeps costs down for the easy cases and unblocks the hard ones.
For broader patterns on browser-driving in scraping, see scraping JavaScript-heavy SPAs with AI agents.
What changes when Cloudflare upgrades to “I’m Under Attack” mode
Cloudflare’s “Under Attack” mode is a separate (and more aggressive) protection layer that adds a JavaScript challenge before any page loads. The challenge solves a proof-of-work computation in JavaScript and issues a
cf_clearancecookie. Without that cookie, every request returns a challenge page.Bypassing Under Attack requires:
- A real or near-real JavaScript engine that can execute the challenge
- Time (the challenge intentionally takes 5-10 seconds)
- The resulting
cf_clearancecookie, used for all subsequent requests within the same session
Tools for this:
- cloudflare-scrape (Python): older, broken since 2023 for most challenges
- cloudscraper (Python): same lineage, semi-maintained
- FlareSolverr: Selenium-based proxy that solves challenges and exposes a REST API for scrapers
- patchright + Playwright: handles the challenge naturally because it runs full Chrome
For Under Attack mode, just use Playwright. Lighter-weight tools struggle.
Detection: how do you know what mode the site is in?
Inspect the response from the protected page:
signal indication HTML contains Turnstile widget regular Turnstile mode HTML contains “Just a moment…” with cf-mitigated header Under Attack JS challenge HTTP 403 with cf-ray header but no challenge body passive failure, no escalation Cookie cf_clearanceset after challengesuccessful challenge solve Cookie __cf_bmsetbasic Cloudflare Bot Management cookie Adapt your bypass strategy to the observed mode. Trying solver-based bypass on Under Attack mode does not work because there is no Turnstile to solve, just a JavaScript challenge.
Operational checklist
For production scrapers facing Turnstile in 2026:
- Use patchright or rebrowser-playwright as default browser
- Verify TLS, canvas, WebGL, audio fingerprints align with real Chrome
- Use clean residential or mobile proxies (no datacenter)
- Add humanization (mouse movement, scroll, pauses) for high-value targets
- Have a third-party solver as fallback for managed-mode failures
- Reuse the same proxy for token harvest and form submission
- Monitor for Cloudflare config changes (mode shifts) on your targets
- Cache and reuse
cf_clearancecookies within their valid window - Log Turnstile success/failure rates per target to detect regressions
Common failure modes
- Token returned but form still fails: token may be IP-bound or expired. Check that you used the same IP and submitted within 5 minutes.
- Token never appears in input: passive checks failed. Improve your stack (cleaner proxy, better fingerprinting).
- Form fails with “Invalid Turnstile response”: check the parameter name. Some sites use
cf-turnstile-response, others use a custom name. Inspect the form to find what is sent. - Solver returns token but verification fails server-side: site may be using Turnstile Enterprise with custom verification, which requires
cdataparameter. Check the widget config fordata-cdata. - Cloudflare Under Attack appears mid-session: the site escalated. Switch to Playwright if not already; the JavaScript challenge needs a real engine.
For broader CAPTCHA strategies, see best CAPTCHA solving services 2026 ranked.
What about Turnstile Enterprise?
Cloudflare Turnstile Enterprise (2024 launch) adds:
- Custom challenge parameters (cdata)
- Pre-clearance integration (pre-solve before form submission)
- Action-specific tokens (login vs registration vs comment)
- Risk score visibility for site operators
For scrapers, the practical impact is that Enterprise sites pass
cdataparameters to the widget that must be submitted with the token. Extractcdatafrom the widget config and pass it to your solver:cdata = await page.evaluate(""" () => { const el = document.querySelector('[data-cdata]'); return el ? el.getAttribute('data-cdata') : null; } """) # Pass to solver result = solve_with_cdata(api_key, sitekey, page_url, cdata)Solvers that support Enterprise (CapSolver, 2Captcha) accept
cdataas an optional parameter.FAQ
Q: is Turnstile easier or harder to bypass than reCAPTCHA?
Easier in some ways (no image challenges), harder in others (more passive fingerprinting). For scrapers with clean stacks, Turnstile often passes silently while reCAPTCHA at least shows a challenge to interact with. Net-net, Turnstile bypass success rates with quality solvers are higher than reCAPTCHA v3 with same-quality solvers.Q: do I need to solve every Turnstile or just on form submissions?
Only on actions that require the token. Reading content protected by Cloudflare Bot Management does not need a Turnstile solve, you just need clean TLS and proxy. Form submissions and certain API calls require the token.Q: can I bypass Turnstile by spoofing the response cookie?
No. The token is verified server-side via Cloudflare’s siteverify, which validates against the issuing flow. Spoofed tokens fail verification.Q: what is the success rate I should expect from third-party solvers?
80-95% depending on the solver and the difficulty of the target site. CapSolver and 2Captcha both publish rates, and your real-world rate depends on how aggressive Cloudflare’s config is for your specific target.Q: how do I tell if my Turnstile bypass is working?
Track form submission success rate over time. If it stays above 90% with stable input, your bypass works. If it drops, Cloudflare changed its rules or your stack drifted.Common pitfalls in production Turnstile bypass
The first failure mode that catches teams off guard is the
__cf_bmcookie lifecycle. Cloudflare issues__cf_bm(Bot Management cookie) on the first request that passes initial scoring, and Turnstile’s internal logic checks for its presence before issuing a token. If your Playwright context starts fresh on every request and discards cookies, Turnstile sees a “first-touch” session with no__cf_bmand runs the full passive battery, which is more likely to fail. The fix is to persist context state across requests within the same proxy IP: usebrowser.new_context(storage_state=stored_state)to carry cookies forward, and only reset state when you rotate to a new proxy.The second pitfall is the action parameter mismatch. Turnstile widgets configured with
data-action="login"produce tokens scoped to that action. Some sites verify server-side that the token’s action matches the endpoint being called. If you harvest a token from a “search” widget on the homepage and submit it to the “/login” endpoint, server-side verification fails with “action mismatch.” Extractdata-actionalongsidedata-sitekeyand pass both to your solver, or harvest tokens from the exact widget instance on the exact page where you intend to use them.The third pitfall is the script.js version drift. Cloudflare ships Turnstile’s challenge JS at
https://challenges.cloudflare.com/turnstile/v0/api.js. The script self-updates and changes its internal challenge logic on a roughly biweekly cadence. Solvers like CapSolver track these changes and update their solving infrastructure within hours of each Cloudflare push. If your scraper has a custom solver implementation (rather than a third-party API), expect to spend half a day every two weeks reverse-engineering the new challenge format. For most teams the math favors paying CapSolver $0.80 per 1000 tokens over maintaining an in-house solver.Real-world example: hybrid harvest-plus-solver pattern
A scraper running against 12 Cloudflare-protected travel sites, each with a different Turnstile configuration, hit the wall trying to use a single bypass strategy. Sites A through D passed with patchright + clean residential IP (zero solver cost). Sites E through I needed CapSolver because their Turnstile config had
cdataaction binding. Sites J through L used Turnstile Enterprise with pre-clearance, which neither pure-passive nor solver-only handled.The fix was a tiered router that classified each site by its Turnstile config and routed accordingly:
async def solve_turnstile(page, sitekey: str, page_url: str, config: dict) -> str: # Tier 1: clean-stack passive if not config.get("cdata") and not config.get("preclearance"): try: await page.wait_for_function( """() => { const i = document.querySelector('[name="cf-turnstile-response"]'); return i && i.value && i.value.length > 100; }""", timeout=8000, ) return await page.evaluate( """() => document.querySelector('[name="cf-turnstile-response"]').value""" ) except Exception: pass # fall through to solver # Tier 2: third-party solver with cdata if present if not config.get("preclearance"): return solve_with_capsolver( CAPSOLVER_KEY, sitekey, page_url, cdata=config.get("cdata") ) # Tier 3: harvest from a maintained real-browser pool with same-IP submission return await harvester.get_token(sitekey, page_url, config.get("action"))After deployment, average cost per successful submit dropped from $1.20 (pure CapSolver) to $0.34 (mixed), and overall success rate rose from 78 percent to 94 percent. The lesson: Turnstile is not one problem, it is several distinct problems sharing a brand name. Classify your targets and route accordingly.
Wrapping up
Turnstile bypass in 2026 is mostly a game of clean fingerprints plus a fallback solver. The simple cases (clean stack, residential IP, properly humanized) pass passively. The hard cases need a third-party solver or token harvesting from real browsers. Match your investment to your targets, monitor success rates, and adapt as Cloudflare rolls out config changes. Pair this guide with DataDome vs PerimeterX vs Akamai bot management and TLS fingerprinting for the surrounding context, and browse the anti-bot-captcha category on DRT for related tactics.
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Behavioral fingerprinting: mouse patterns, timing, typing
Behavioral fingerprinting: mouse patterns, timing, typing
Behavioral fingerprinting is what catches scrapers after they have fixed everything else. TLS, HTTP/2, canvas, WebGL, audio, fonts, all clean. The browser looks like Chrome, sounds like Chrome, hashes like Chrome. Then the script clicks a login button without ever moving the mouse to it, fills a form with characters typed in 4 milliseconds each, and the bot detector logs a session that no human could possibly produce. The hashes were perfect, the behavior was the giveaway.
This guide covers what behavioral fingerprinting actually measures, why simple
page.clickandpage.fillcalls in Playwright are detectable, and the patterns that produce realistic interactions. Code targets Playwright with Chromium because that is the dominant scraping browser, but the principles apply across automation stacks.What behavioral fingerprinting measures
Modern bot-detection vendors instrument the page with JavaScript that records:
- Mouse path: every mousemove event, with coordinates, timestamp, and pressure (where supported)
- Mouse velocity: speed and acceleration patterns between mousemoves
- Mouse click timing: time between mousedown and mouseup, click frequency, double-click cadence
- Scroll patterns: scroll start/end coordinates, velocity, smoothness, deltaY values
- Touch events: similar to mouse but for touch devices
- Keystroke timing: dwell time per key, flight time between keys, typing rhythm
- Focus and blur events: window focus changes, tab switches, time spent on each input
- Page lifecycle: time-to-first-interaction, scroll-to-bottom timing, total session duration
- Pointer events: pointertype (mouse, touch, pen), pressure, tilt
- Sensor events on mobile: device orientation, motion, when permission is granted
Each of these is captured at high frequency (often hundreds of events per second), aggregated, and fed into a model that scores the session for likelihood-of-being-human. Real humans produce noisy, variable patterns. Default Playwright actions produce sterile, deterministic patterns that the model recognizes within seconds.
Vendors that heavily use behavioral fingerprinting in 2026:
- DataDome (proprietary behavioral model)
- PerimeterX / Human Security (very behavior-heavy)
- Akamai Bot Manager (behavior is one of many signals)
- Kasada (aggressive behavioral and challenge-based)
- reCAPTCHA v3 (behavior-only, no challenge)
- Cloudflare Turnstile (passive behavioral checks)
For a deeper academic background, see Anti-bot bypass: a look at modern browser fingerprinting, which surveys behavioral signals among other techniques.
What default Playwright leaks
Default
page.click("button.submit")in Playwright produces:- One mousemove event from current position to target center
- One mousedown at exact center of target
- One mouseup at the same coordinates 50ms later
- One click event
Real human clicks produce:
- 5-30 mousemove events along a curved path
- mousedown at a slightly off-center coordinate
- mouseup 80-300ms later, sometimes at a slightly different coordinate (hand jitter)
- A click at the final position
The default automation pattern is so different from human behavior that vendors can flag it from a single click. Same for
page.fill("input", "username"):- All characters appear in input value within milliseconds
- No keydown/keyup/keypress events fire (Playwright bypasses keyboard events for fill)
- No focus event before, no blur event after
- No selectionchange events
A human typing “username” produces:
- focus event on the input
- 8 keydown events (dwell time 50-150ms each)
- 8 keypress events (one per character)
- 8 keyup events
- 7 flight times between keys (60-200ms each, with variable patterns)
- Several selectionchange events as the cursor moves
- blur event when leaving the field
Default
page.fillproduces zero of these. The fix is to usepage.type(which does fire events) plus realistic timing, plus mouse movement to the field before typing.Bypass approach 1: realistic mouse paths with Bezier curves
Replace direct
page.mouse.click(x, y)calls with a path that curves toward the target, varies speed, and overshoots slightly before settling. Bezier curves are the standard approach.import asyncio import random from playwright.async_api import async_playwright, Page async def human_mouse_move(page: Page, x_target: int, y_target: int, steps: int = 25): """Move the mouse along a bezier curve from current position to target.""" # Get current mouse position via injected JS pos = await page.evaluate( "() => ({ x: window.__mx || 100, y: window.__my || 100 })" ) x_start, y_start = pos["x"], pos["y"] # Generate two random control points cx1 = x_start + random.randint(-100, 100) cy1 = y_start + random.randint(-100, 100) cx2 = x_target + random.randint(-100, 100) cy2 = y_target + random.randint(-100, 100) def bezier_point(t): x = ((1 - t) ** 3) * x_start + 3 * ((1 - t) ** 2) * t * cx1 \ + 3 * (1 - t) * (t ** 2) * cx2 + (t ** 3) * x_target y = ((1 - t) ** 3) * y_start + 3 * ((1 - t) ** 2) * t * cy1 \ + 3 * (1 - t) * (t ** 2) * cy2 + (t ** 3) * y_target return int(x), int(y) for i in range(steps + 1): t = i / steps # Add slight non-linearity to t for variable speed t_eased = 1 - (1 - t) ** 2 x, y = bezier_point(t_eased) await page.mouse.move(x, y) # Track current position await page.evaluate(f"() => {{ window.__mx = {x}; window.__my = {y}; }}") # Variable delay per step await asyncio.sleep(random.uniform(0.005, 0.015)) async def human_click(page: Page, selector: str): """Click an element with realistic mouse movement, jitter, and timing.""" box = await page.locator(selector).bounding_box() if not box: return # Pick a slightly random coordinate within the element x = int(box["x"] + box["width"] * random.uniform(0.3, 0.7)) y = int(box["y"] + box["height"] * random.uniform(0.3, 0.7)) await human_mouse_move(page, x, y) # Brief pause before click (humans pause to "aim") await asyncio.sleep(random.uniform(0.05, 0.2)) await page.mouse.down() # Variable mousedown duration await asyncio.sleep(random.uniform(0.08, 0.18)) # Slight position drift during press x_up = x + random.randint(-2, 2) y_up = y + random.randint(-2, 2) await page.mouse.move(x_up, y_up) await page.mouse.up()This produces a mouse trace that looks like a human pointing at and clicking on the button. The Bezier path curves naturally, the speed varies, the click is slightly off-center, and the mousedown holds for 80-180ms with a tiny drift before mouseup.
Bypass approach 2: realistic keyboard timing
Replace
page.fillwithpage.type(which does fire keyboard events) plus realistic per-character delays:import asyncio import random from playwright.async_api import Page # Average dwell and flight times by character type, in milliseconds DWELL_BASE_MS = 80 FLIGHT_BASE_MS = 120 async def human_type(page: Page, selector: str, text: str): """Type text into an input with realistic per-character timing.""" await page.locator(selector).click() # focus the field with a real click await asyncio.sleep(random.uniform(0.2, 0.4)) # pause to "look at the field" for i, char in enumerate(text): # Dwell time (time key is pressed) dwell = DWELL_BASE_MS + random.randint(-30, 50) await page.keyboard.down(char) await asyncio.sleep(dwell / 1000) await page.keyboard.up(char) # Flight time (between keys) if i < len(text) - 1: flight = FLIGHT_BASE_MS + random.randint(-50, 100) # Common bigrams are faster if text[i:i+2] in ["th", "he", "in", "er", "an", "re"]: flight = int(flight * 0.7) # Number-letter transitions are slower elif text[i].isdigit() != text[i+1].isdigit(): flight = int(flight * 1.3) await asyncio.sleep(flight / 1000) # Brief pause after typing complete await asyncio.sleep(random.uniform(0.3, 0.6))This produces a keystroke trace with variable dwell and flight times that pattern-match common typing rhythms. Bigram-aware flight times (
th,he,infaster than rare combinations) push the realism further.Bypass approach 3: scroll behavior
Page scrolling is another high-resolution behavioral signal. Instant
page.mouse.wheel(0, 1000)is detectable. Scroll in small increments with variable timing:import asyncio import random from playwright.async_api import Page async def human_scroll(page: Page, total_pixels: int, direction: str = "down"): """Scroll the page in small increments with variable timing.""" sign = 1 if direction == "down" else -1 remaining = total_pixels while remaining > 0: # Each "scroll wheel notch" is 100-300 pixels chunk = random.randint(80, 250) chunk = min(chunk, remaining) await page.mouse.wheel(0, sign * chunk) remaining -= chunk # Pause between scroll chunks await asyncio.sleep(random.uniform(0.1, 0.4)) # Sometimes pause after scrolling complete to "read" if random.random() < 0.6: await asyncio.sleep(random.uniform(1.0, 3.0))For pages with infinite scroll, alternate scroll-and-pause patterns mimic the read-then-scroll cadence of real users. For pages with discrete content, occasionally scroll back up a bit (humans often do) to add more variety.
Bypass approach 4: full session lifecycle
Beyond individual actions, behavioral fingerprinting also looks at the macro shape of a session:
- Time from page load to first interaction (humans take 1-5 seconds, bots often interact immediately)
- Whether the user moves the mouse before clicking
- Whether the user reads (scrolls slowly) before submitting forms
- Time spent on each page before navigating away
- Tab switches and window blur events
A complete realistic session:
async def realistic_visit(page, url: str): await page.goto(url, wait_until="domcontentloaded") # Initial settle: humans don't act on the page in the first second await asyncio.sleep(random.uniform(1.5, 4.0)) # Move mouse around aimlessly while "reading" for _ in range(random.randint(2, 5)): x = random.randint(200, 1200) y = random.randint(200, 800) await human_mouse_move(page, x, y, steps=15) await asyncio.sleep(random.uniform(0.5, 1.5)) # Scroll partway down the page await human_scroll(page, random.randint(300, 800)) # Read a bit more await asyncio.sleep(random.uniform(2.0, 5.0)) # Now perform the actual scrape action (e.g., click a product) await human_click(page, ".product-card:first-child a")This pattern adds 5-10 seconds per page, which slows scraping. The tradeoff is real: slower but unblocked, or faster but blocked. For high-value targets, the slowdown is worth it.
Comparison: detection difficulty by signal
signal difficulty to spoof impact if wrong mouse path linearity low (use Bezier curves) high (immediate flag) mouse jitter low (add per-step random) medium click timing low (random mousedown duration) medium keystroke dwell time medium (per-key timing) high keystroke flight time medium (bigram awareness) high scroll smoothness low (chunked wheel events) medium time-to-first-interaction trivial (sleep) high focus and blur events medium (manage event firing) medium pointer pressure hard (most automation lacks pressure) low for desktop, medium for mobile sensor events on mobile hard (no real device motion) high for mobile The high-impact, low-difficulty signals (mouse path, time-to-first-interaction, scroll patterns) should be your first targets. Pointer pressure and sensor events matter less unless you are scraping a mobile-only site.
Bypass approach 5: third-party humanization libraries
Several libraries package realistic interaction patterns into single-call helpers:
- botright: Python library that wraps Playwright with realistic Bezier mouse paths, typing patterns, and other humanization
- puppeteer-extra-plugin-humanize: Node.js equivalent for Puppeteer
- playwright-extra with stealth: stealth plus humanization
- Stagehand: AI-driven, includes realistic interaction by default
- Browserbase: managed service with humanization built in
Using botright in Python:
from botright import Botright async def stealth_with_human_actions(url: str): botright_client = await Botright(headless=True) browser = await botright_client.new_browser() page = await browser.new_page() await page.goto(url) # botright's enhanced page object includes realistic actions await page.mouse.click(500, 300) # uses bezier mouse internally await page.keyboard.type("hello", delay=120) # uses realistic per-key delay await botright_client.close()For most teams, a stealth library plus careful selector-level humanization on the actions you care about is the right balance.
Verifying behavioral fingerprinting
Unlike TLS or canvas, behavioral fingerprinting cannot be checked against a single public site that returns a hash. The signal is captured by site-side JavaScript and only visible in the bot vendor’s backend. Practical verification:
- Run against a known-protected site: pick a site you know uses DataDome or PerimeterX (
fingerprint.com/demoexposes some signals, ticketing sites like SeatGeek run heavy bot defenses) - Compare success rate: vary your behavioral patterns and measure the resulting block rate
- Use shadow accounts: run the same scraping flow with realistic human behavior (recorded from a real user) versus default Playwright, compare outcomes
- Inspect the captured signal: use browser DevTools to inspect what the bot vendor’s JavaScript is sending in network requests; compare your scraper’s payload structure to a real user’s
For statistical sanity-checking your typing patterns, real users have a coefficient of variation in flight times around 0.3-0.5 (standard deviation divided by mean). If your scraper produces flight times with CV near 0, you are flagged.
Operational checklist
For production scrapers facing behavioral fingerprinting in 2026:
- Replace
page.clickwith humanized click that includes mouse movement - Replace
page.fillwithpage.typeplus realistic per-character delays - Add 1-5 second pause between page load and first interaction
- Scroll in chunks, not all-at-once
- Add brief pauses after each major action (read, navigate, decide)
- Use bigram-aware typing speeds for forms
- Pair with TLS, canvas, WebGL, audio defenses
- Use clean residential or mobile proxies (behavioral cleanliness does not save you on a flagged IP)
- Vary the session shape across pages (different scroll depths, different read times)
- Avoid running multiple browser contexts from the same IP simultaneously (shared timing patterns are a flag)
Red flags that bot vendors specifically watch for
Common patterns that get sessions flagged in 2026:
- Mouse never moves before a click
- Mouse moves in perfectly straight lines
- Click coordinates are dead-center on every target
- Form fields filled with no keydown/keyup events
- Submit button clicked within 100ms of last field fill
- Page never scrolls below the fold but a full data extraction was performed
- Time-to-first-interaction less than 500ms
- Identical session shape (same actions, same timing) across multiple page loads
- No idle time anywhere in the session
- Tab focus never blurs (real users switch tabs)
- viewport size is exactly default Chrome (1280×720) on every session
Avoiding all of these requires deliberate effort. Default Playwright produces several of them automatically.
Mobile-specific behavioral signals
If you are scraping mobile-targeted content, mobile-specific signals add to the surface:
- Touch events: pointertype “touch” rather than “mouse”
- Tap timing: time between touchstart and touchend (real taps are 50-200ms)
- Swipe gestures: required for some mobile flows
- DeviceMotion and DeviceOrientation events: real phones have constant low-magnitude motion noise
Spoofing mobile motion requires injecting fake DeviceMotion events at realistic frequencies (30-60Hz with small accelerometer noise). patchright includes this for mobile profiles.
For broader anti-bot patterns, see DataDome vs PerimeterX vs Akamai bot management compared and Cloudflare Turnstile bypass tactics.
When behavioral fingerprinting is the dominant signal
For some sites, behavioral signals dominate everything else:
- Ticketing sites during high-demand drops
- Sneaker drop sites (Snkrs, ConfirmedApp)
- Account creation flows on social media
- Banking and fintech logins
- Government services (visa applications, tax filings)
For these targets, perfect TLS and clean proxies do not help if your behavior screams bot. Invest in humanization.
For other sites, behavioral signals matter less:
- Public news scraping (no behavioral check on read)
- Search engine results pages (some checks but mostly proxy/TLS)
- API endpoints without browser flow
- Static content scraping
Match your humanization investment to the target value.
Sample full session: realistic product scrape
Putting it all together for an ecommerce product scrape:
async def scrape_product(page, product_url: str): await page.goto(product_url, wait_until="domcontentloaded") await asyncio.sleep(random.uniform(2, 4)) # initial read # Move mouse to scroll area await human_mouse_move(page, 600, 400) await asyncio.sleep(0.5) # Scroll to see product details await human_scroll(page, 500) await asyncio.sleep(random.uniform(2, 5)) # Hover over price element (realistic mouseover) await human_mouse_move(page, 800, 350, steps=20) await asyncio.sleep(0.8) # Read description by scrolling more await human_scroll(page, 400) await asyncio.sleep(random.uniform(3, 6)) # Now extract data without further interaction title = await page.text_content("h1.product-title") price = await page.text_content(".price-current") description = await page.text_content(".product-description") return {"title": title, "price": price, "description": description}This takes 8-15 seconds per product, versus 1-2 seconds for a default Playwright fetch. The slowdown is the price of unblocking. Plan throughput accordingly.
FAQ
Q: do I need to humanize behavior on every page or just on form submissions?
For PerimeterX, DataDome, Kasada targets, every page. They collect signals throughout the session. For lighter targets, only on critical actions like form submits and high-value clicks.Q: can I record real human behavior and replay it?
You can but it is risky. Recorded behavior gets reused identically across sessions, which itself becomes a fingerprint. Better to parametrize realistic patterns (Bezier with random control points, variable typing speeds) so each session is unique.Q: how do I know if behavioral fingerprinting is what is blocking me?
Look at when the block happens. Immediate 403 on first request: likely TLS or proxy. Block after a few minutes of activity: likely behavioral. Block after submitting a form: definitely behavioral. The timing of the block tells you which layer caught you.Q: does adding random sleeps work?
Random sleeps help but are not enough. The shape of the behavior matters too: paths, pressure, event sequences. Random sleeps without humanized actions just slow down a still-detectable bot.Q: are mobile sessions easier or harder to humanize than desktop?
Harder. Mobile adds touch events, sensor noise, and orientation changes that are difficult to fake convincingly. patchright handles the basics, but truly convincing mobile sessions need device emulation that few stealth libraries provide.Q: how many mousemove events per second should a humanized session emit?
Real desktop browsing emits roughly 60-120 mousemove events per second when the cursor is in motion, dropping to zero when idle. PerimeterX flags any session that emits a constant rate above 200 events per second (suggests scripted high-resolution path) or below 20 events per second during active interaction (suggests skipped intermediates). Target a Poisson-distributed event rate around 80 per second during motion with realistic idle gaps.Wrapping up
Behavioral fingerprinting is the layer that sorts careful scrapers from sloppy ones. Once your stack handles TLS, HTTP/2, canvas, WebGL, and audio, behavior is the last big thing to get right. Bezier mouse paths, realistic typing rhythms, chunked scrolls, and full session pacing add 5-10 seconds per page but unlock targets that defeat lighter approaches. Pair this with our TLS fingerprinting guide, canvas fingerprinting bypass, and WebGL fingerprinting bypass for the full picture, and browse the anti-detect-browsers category on DRT for related deep-dives.