obscura

Obscura

Single-developer, open-source Rust headless browser. Boots instantly, ~70 MB binary, ~30 MB RAM at runtime, and serves a Chrome DevTools Protocol port that Puppeteer and Playwright connect to unchanged. You swap the binary, not the code.

Repo: https://github.com/h4ckf0r0day/obscura

Why pick Obscura over Chrome

Field measurement on Cloudflare-protected nairaland.com (warm fetch): Obscura ~4.1–4.9 s, returns real HTML body. Real Chrome over CDP: ~5.1 s warm / 9.3 s cold. curl: 0.5–0.9 s but only the CF challenge interstitial.

Obscura is roughly as fast as warm Chrome, ~2× faster cold, parallelizes far better because it doesn't carry Chrome's per-process overhead, and clears Cloudflare's basic JS challenge without the stealth feature.

Build

git clone https://github.com/h4ckf0r0day/obscura.git
cd obscura
CARGO_TARGET_DIR=/tmp/obscura-target cargo build -p obscura-cli --bin obscura

Resulting binary: /tmp/obscura-target/debug/obscura

The default build has no stealth and needs no extra tools. Stealth is opt-in (see below) and pulls wreq / BoringSSL, so it needs cmake locally.

Stealth build

CARGO_TARGET_DIR=/tmp/obscura-target cargo build -p obscura-cli --bin obscura --features stealth

What stealth gives you:

• Consistent browser fingerprint so cross-layer checks pass: the TLS ClientHello, User-Agent, navigator surfaces, and WebGL renderer all agree on one Chrome identity rather than contradicting each other
• 3,520 tracker domains blocked (built-in blocklist)
• navigator.webdriver masked
• Native functions patched so common automation detectors can't unmask them via Function.prototype.toString inspection
• TLS / HTTP-2 fingerprint matching real Chromium (defeats most JA3/JA4 + ALPN-ordering bot management)

Enable it at runtime with the global --stealth flag (works on fetch, serve, scrape, and mcp, before or after the subcommand). The flag needs a stealth-feature build for the TLS layer; without it --stealth still does tracker blocking.

/tmp/obscura-target/debug/obscura fetch https://example.com/ --stealth --dump text

Use stealth against: Cloudflare Turnstile non-interactive, Akamai BMP, PerimeterX, DataDome. Stealth still won't clear: hard interactive CAPTCHAs (Turnstile interactive, hCaptcha challenge), and fingerprinters using WebGPU/WebAssembly quirks not yet patched.

CLI fetch

/tmp/obscura-target/debug/obscura fetch https://example.com/ --dump text --quiet

Useful flags:

• --dump text: visible text only
• --dump html: full rendered DOM
• --dump assets: every external resource plus fetch()/XHR URLs, one JSON object per line
• --dump cookies: all cookies as JSON, including HttpOnly
• --quiet: suppress progress logs
• --timeout <ms>: per-page timeout

CDP server (Puppeteer / Playwright)

/tmp/obscura-target/debug/obscura serve --port 9222

Playwright:

import { chromium } from "playwright-core";

const browser = await chromium.connectOverCDP("ws://127.0.0.1:9222");
const page = await browser.newContext().then((ctx) => ctx.newPage());
await page.goto("https://example.com/");
console.log(await page.title());
await browser.close();

Puppeteer:

import puppeteer from "puppeteer-core";

const browser = await puppeteer.connect({
  browserWSEndpoint: "ws://127.0.0.1:9222/devtools/browser",
});
const page = await browser.newPage();
await page.goto("https://example.com/");
console.log(await page.title());
await browser.disconnect();

Request interception

Over CDP, page.setRequestInterception(true) (Puppeteer) or page.route (Playwright) block, modify, or mock requests as usual. Embedding the engine with the obscura Rust crate gives the same thing as a native Page API: on_request / on_response callbacks (capture SPA API payloads without reverse-engineering the bundle), an enable_interception() channel to block, mock, or rewrite, and add_preload_script to run code before the page's own scripts.

Scaling profile

• ✅ High concurrency, low resource: static + lightly-dynamic pages — hundreds of parallel fetches per box.
• ⚠️ Medium: JS-rendered SPAs, light bot protection — works but slower than raw HTTP, watch timeouts.
• ❌ Low / unreliable: aggressive bot defense (Turnstile interactive, Akamai BMP), real auth-walled apps, anything needing pixel-perfect rendering parity with Chrome.

Known limits

• Not full Chrome — some browser APIs and CDP methods are incomplete relative to upstream Chromium.
• Screenshot capture is not implemented (no layout/rendering engine).
• Authenticated pages need cookie or session injection via CDP; Obscura won't run interactive logins.
• Hard CAPTCHAs (Turnstile interactive, hCaptcha) require a human or a third-party solver.

Safety

Treat Obscura like any external Rust crate: cargo build runs dependency build scripts (V8, TLS). Build into a disposable target dir (CARGO_TARGET_DIR=/tmp/obscura-target) when evaluating new branches.