clark-browser

by Clark — MIT licensed

Stealth Chromium for browser automation. Anti-fingerprinting compiled into the binary at the C++ source level — not a JavaScript injection, not a config patch.

What this is

A fork of ungoogled-chromium 148.0.7778.96 with a patch series that makes the binary indistinguishable from a real Chrome install across the JS-visible fingerprint surface (navigator properties, WebGL GPU strings, screen dimensions, plugins, timezones, etc.).

The patched binary is MIT-licensed — this is an open-source project, not a commercial-licensed stealth browser like CloakBrowser or Multilogin. Build it from source yourself, or use the prebuilt binaries from GitHub Releases.

Why

Stock chromium --headless is trivially detectable: navigator.webdriver = true, empty plugin list, HeadlessChrome in the User-Agent, software-renderer WebGL strings, and a dozen other signals that detection sites grep for. JS-level "stealth" shims (puppeteer-extra-plugin-stealth, playwright-stealth, undetected- chromedriver) only paper over the surface — sites like FingerprintJS, BrowserScan, and Cloudflare Turnstile catch them because the patches themselves are detectable.

clark-browser patches Chromium where the values come from — at the C++ source level, in blink/v8/net — so detection sites just see "a normal Chrome install."

Supported platforms

Platform	Status
Linux x86_64	prebuilt binary in releases
macOS arm64	prebuilt binary in releases

Other targets (macOS x86_64, Windows) need a source build.

Usage

Install the Python wrapper from PyPI:

pip install clark-browser

Use it as a Playwright launcher. The wrapper downloads the matching patched Chromium build from GitHub Releases on first launch and caches it under ~/.clarkbrowser/.

from clarkbrowser import launch

browser = launch()
page = browser.new_page()
page.goto("https://bot.sannysoft.com")
print(page.title())
browser.close()

You can also prefetch or inspect the browser binary with the CLI:

clark-browser info
clark-browser fetch

For Vercel agent-browser usage, see examples/agent_browser.md.

For direct CDP usage, download the tarball for your platform from the releases page, extract it, and run the binary directly. Drive it via any Chrome DevTools Protocol client (CDP over HTTP/WebSocket).

# Linux: extract and launch with CDP on port 9222
tar -xzf clark-browser-linux-x64.tar.gz
./headless_shell \
  --headless=new \
  --remote-debugging-port=9222 \
  --remote-allow-origins=* \
  --fingerprint=12345 \
  --fingerprint-platform=windows \
  about:blank

The Linux tarball contains the headless_shell binary (~270 MB), a chrome compatibility launcher, headless resource packs, and runtime helper libraries. The macOS arm64 build produces a normal Chromium.app bundle.

Stealth surface

--fingerprint-* switches drive the patches. All have seed-derived defaults when omitted — pass --fingerprint=<integer> for a deterministic identity, or let the binary pick a fresh seed at startup for per-launch variation.

--fingerprint=<int>              master RNG seed (10000..99999)
--fingerprint-platform=          windows | macos | linux
--fingerprint-platform-version=  client hints platform version
--fingerprint-brand=             Chrome | Edge | Opera | Vivaldi
--fingerprint-brand-version=
--fingerprint-gpu-vendor=        WebGL UNMASKED_VENDOR_WEBGL
--fingerprint-gpu-renderer=      WebGL UNMASKED_RENDERER_WEBGL
--fingerprint-hardware-concurrency=
--fingerprint-device-memory=     in GB
--fingerprint-screen-width=
--fingerprint-screen-height=
--fingerprint-taskbar-height=    Win=48, Mac=95, Linux=0
--fingerprint-storage-quota=     in MB
--fingerprint-timezone=          IANA tz, e.g. America/New_York
--fingerprint-locale=            BCP 47
--fingerprint-fonts-dir=         path to platform font directory
--fingerprint-location=          lat,lon for geolocation API
--fingerprint-webrtc-ip=         literal IPv4 to spoof in ICE candidates
--fingerprint-noise=             true | false  (canvas/audio noise on/off)

Verified-working patches

Confirmed firing in CDP-driven smoke tests against the built binary (tests/linux_smoke.py, tests/integration_smoke.py):

Detection vector	Patched	Verification
navigator.webdriver	always false	navigator.webdriver === false
navigator.plugins	5 PDF-viewer entries	navigator.plugins.length === 5
window.chrome	always an object	typeof window.chrome === "object"
navigator.platform	spoofed from --fingerprint-platform	returns "Win32" under =windows
navigator.userAgentData	brand/platform/version coherent with spoofed UA	returns Windows + Google Chrome under =windows
navigator.hardwareConcurrency	seed-derived from {4, 6, 8, 12, 16}	deterministic per seed
navigator.maxTouchPoints	matched to platform	0 on =windows
timezone / locale	from --fingerprint-timezone / --locale	reaches Blink as set
User-Agent	no HeadlessChrome	full Chrome UA under --user-agent=...
Audio fingerprint	seed-derived deterministic noise	two distinct seeds yield distinct audio FP

See PATCHES.md for the full patch catalog and specs/ for per-category implementation notes.

Methodology

We build on ungoogled-chromium (BSD-3) and inherit its existing Brave-derived canvas/audio/clientRects noise infrastructure. Our patches are written from public sources only — W3C specs, Chromium upstream code, MDN bot-detection writeups, and curl-impersonate (MIT). We do not reverse-engineer or copy from any proprietary stealth-browser binary. See METHODOLOGY.md.

Building from source

# 1. Fetch tooling
git clone https://github.com/clark-labs-inc/clark-browser
cd clark-browser

# 2. Fetch Chromium 148 source (~17 GB, ~30 min)
./build/fetch-source.sh

# 3. Apply patches (instant)
./build/apply-patches.sh

# 4. Build (4–12 hours, ~80 GB disk, 32+ GB RAM recommended)
./build/build.sh

For a clean Linux x86_64 build that mirrors what ships in our releases, use ./build/build-linux.sh instead (runs the full clone → patch → ninja pipeline in a single script; designed for fresh Ubuntu hosts).

See build/README.md for detailed prerequisites.

License

MIT. ungoogled-chromium and Chromium upstream components retain their respective BSD/MPL/other licenses; this project does not modify those.

Status

Alpha. Linux x86_64 and macOS arm64 builds are reproducible end-to-end and the patches above are runtime-confirmed against the built binary. The remaining patches in the series compile in but need broader detection-site benchmarking. Contributions welcome — see specs/ for the patch backlog.