Drive stealth Chromium to bypass bot detection in web automation

One browser engine to rule them all

Stealth Chromium engine

Fortress is a stealth Chromium engine that stops your scrapers and browser agents from getting blocked, with one line of code change. Bot detectors flag automation by reading the browser fingerprint; Fortress corrects that fingerprint inside Chromium's C++, so the browser presents as an ordinary Chrome install. Scrapers finish their runs, agents reach the pages they were sent to, and CreepJS, Sannysoft, BrowserScan, and live Cloudflare Turnstile all read it as human. Point your existing Playwright or Puppeteer at Fortress over CDP, and nothing else in your code changes.

_{Blink · V8 · BoringSSL patched in-tree · ANGLE / D3D11-backed WebGL · JA3/JA4-coherent TLS · monthly upstream rebase · reproducible, gauntlet-gated releases}

34 single-surface C++ patches

0% CreepJS headless / stealth

[native code] across every realm

BSD-3 open engine, rebuild it yourself

_{Unedited capture of the Fortress binary in a real window: it clears a live Cloudflare challenge, turns bot.sannysoft.com all green, then reads BrowserScan “Normal”. Reproduce with tools/gauntlet.py.}

What's new - 151.0.7908.0 · Engine Refresh

Released. Per-launch coherent personas, hardened.

• Per-locale keyboard (QWERTY / QWERTZ / AZERTY) · per-persona media devices · a full delivery-parity coherence pass.
• Platform ↔ GPU ↔ timezone ↔ language ↔ voices ↔ keyboard move as one coherent real device - on every launch, from a single binary.
• Native-code parity (toString() stays [native code]), realm-invariant (main / worker / iframe) - coherence compiled into the browser, not patched in JavaScript.

pip install -U tilion-fortress       # or:  docker run --rm -p 9222:9222 tilion/fortress:latest

→ full release notes

Contents

What it is

Fortress is a Chromium fork that spoofs the browser fingerprint from inside the engine. The surfaces bot detectors read (canvas, WebGL, audio, fonts, navigator, and about thirty more) are corrected in Chromium's C++, with no JavaScript patch layer sitting on top for a page to catch.

It ships as an ordinary browser binary that exposes a CDP endpoint. Point Playwright, Puppeteer, or any CDP client at it and your existing automation runs unchanged.

A JavaScript stealth patch leaves an extra layer the page can find: .toString() shows the override's source, and re-grabbing the same primitive from an iframe or worker reaches past it. Fortress corrects the surface in the engine instead, so navigator.vendor resolves to the real C++ getter, reports [native code], and reads the same from every realm. A page inspecting itself sees stock Chromium. That is why your automation gets through where it used to get flagged, and whatever blocking is left traces to your proxies and behavior rather than the browser. Why patch the engine, not the page covers the detection mechanics in full.

from tilion_fortress import Fortress
from playwright.sync_api import sync_playwright

with Fortress() as f:                                   # launches the stealth engine on a CDP endpoint
    with sync_playwright() as p:
        browser = p.chromium.connect_over_cdp(f.cdp_url)
        page = browser.new_page()
        page.goto("https://bot.sannysoft.com")
        page.screenshot(path="all-green.png")

import { Fortress } from "tilion-fortress";
import { chromium } from "playwright";

const f = await Fortress.launch();                      // stealth engine on a CDP endpoint
const browser = await chromium.connectOverCDP(f.cdpUrl);
const page = await browser.newPage();
await page.goto("https://browserscan.net");
await browser.close();
await f.close();

The 12-second tour

_{One loop, all real captures: passes CreepJS / Sannysoft / BrowserScan / rebrowser → scrapes structured data over CDP → clears Akamai on aa.com · lowes · macys · kohls (same residential IP).}

Real scraping, fully headless

_{Unedited captures of the Fortress engine driven over CDP. No stealth plugins, no JS patches: the fingerprint is corrected in the binary. Reproduce any of these with examples/scrape_demos.py.}

_{Structured extraction: records build into typed JSON as each item is read.}

Auto-pagination: 30 quotes across 3 pages.

Deep detail crawl: UPC · price · tax · stock · reviews.

Clears real Akamai - before / after

_{Same residential IP, same site (aa.com · Akamai Bot Manager). A stock/headless browser gets Access Denied (Reference #); Fortress loads the real page and Akamai issues its _abck sensor cookie - the Bot Manager accepts it as a real browser. The variable is the fingerprint, not the IP.}

lowes.com · blocked → cleared

macys.com · blocked → cleared

kohls.com · blocked → cleared

_{Not a one-site fluke - same before/after on major Akamai-protected retailers, every run from the same residential IP.}

Quick start

# Python / Node: prebuilt native binary auto-fetched (Linux x64 & Windows x64), SHA-256 verified
pip install tilion-fortress
npm  install tilion-fortress

# Any OS via Docker: raw CDP on :9222  (~302 MB pull / 851 MB on disk, stripped single-layer)
docker run --rm -p 9222:9222 tilion/fortress:latest

# Portable bundle (extract-and-run, like a Chromium snapshot)
tar xzf tilion-fortress-linux-x64.tar.gz            # Linux
./tilion-fortress/tilion --headless=new --remote-debugging-port=9222 --user-data-dir=/tmp/p

# Debian / Ubuntu
sudo apt install ./tilion-fortress_151.0.7908.0_amd64.deb && tilion https://example.com

Versions

Fortress ships on two Chromium bases - pick your trade-off between blend-in and currency:

Fortress().start()                     # Python: stable (149) by default
Fortress(channel="latest").start()     # opt into 151

await Fortress.launch();               // Node: stable (149) by default
await Fortress.launch({ channel: "latest" });

docker run --rm -p 9222:9222 tilion/fortress:149   # or :151
# or set FORTRESS_CHANNEL=latest for either SDK

Native binaries: Linux x64 (both versions) + Windows x64 (151); Windows-149 and macOS run via the Docker image.

Drop it into your AI agent

Fortress is the browser your agent drives: raw CDP on :9222, no stealth plugins to wire up. There are two ways in.

Option 1: open it pre-loaded in a chat assistant. One click; it reads our AGENTS.md and walks you through the whole setup:

Option 2: Copy for agent (everything, to your clipboard). Hit the copy icon at the top-right of the box below. It puts the entire setup context on your clipboard: what it is, install, connect, persona, and rules, all of AGENTS.md condensed. Paste it into Cursor, Claude Code, Copilot, ChatGPT, or any agent and it takes it from there:

You're setting up Fortress, an open-source STEALTH Chromium engine, for browser automation.
It corrects the browser fingerprint (canvas, WebGL, audio, fonts, navigator, +30 more) in Chromium's
C++ and exposes raw CDP on http://localhost:9222, a drop-in for Playwright/Puppeteer. Do NOT add
puppeteer-stealth or any JS fingerprint patching (it self-reveals and undoes Fortress).

LAUNCH (pick one; all expose CDP on http://localhost:9222):
  Docker:  docker run -d --rm -p 9222:9222 tilion/fortress:latest
  Python:  pip install tilion-fortress    then  from tilion_fortress import Fortress; f=Fortress(); f.start()
  Node:    npm install tilion-fortress    then  import {Fortress} from "tilion-fortress"; const f=await Fortress.launch()

CONNECT (keep my existing automation code):
  Playwright(py):  browser = p.chromium.connect_over_cdp("http://localhost:9222")
  Playwright(js):  const browser = await chromium.connectOverCDP("http://localhost:9222")
  Puppeteer(js):   const browser = await puppeteer.connect({ browserURL: "http://localhost:9222" })
  browser-use / Crawl4AI / Stagehand / LangChain:  point their CDP endpoint at http://localhost:9222

PERSONA (optional; default is a coherent Windows identity). Override any surface with --uxr-* flags:
  --uxr-timezone=America/New_York --uxr-hw-concurrency=16 --uxr-languages=en-US,en

RULES:
  1) Drive over raw CDP (:9222); don't spawn chromedriver.
  2) Never pass --user-agent (use --uxr-ua-*); it desyncs UA vs UA-Client-Hints.
  3) No puppeteer-stealth / undetected-chromedriver / JS fingerprint patches.
  4) Blocked ~90% = my IP (datacenter), not the fingerprint. Use a residential/mobile proxy, then retry.

Now walk me through launching Fortress and wiring my automation to it.
Full guide: https://github.com/tiliondev/fortress/blob/main/AGENTS.md

The Fortress MCP - stealth browsing as agent tools  _Beta

Raw CDP is for code you write. The Fortress MCP is for agents that call tools: a Model Context Protocol server that hands Claude, Cursor, or any MCP client a stealth browser, so the moment a fetch is blocked it just calls a tool and gets the page. 29 tools, local and free - fetch_protected_page, extract_page, crawl_site, recon_site_apis, search_web, run_browser_task, save_profile, get_stealth_cdp_endpoint, and more.

_{Real, dated run against stockx.com (PerimeterX). A stock browser gets HTTP 403 - “Access denied”; an agent with the Fortress MCP returns clean JSON - same site, same prompt. Reproduce it from the framework repo.}

Set it up in 30 seconds

Two runners - pick one. npx needs Python on PATH; pip installs it directly:

pip install "tilion[mcp]"      # command:  tilion-mcp
#   —or, zero-install—
npx -y tilion-mcp              # auto-runs the server via uv (no global install)

Claude Desktop - Settings → Developer → Edit Config (claude_desktop_config.json):

{ "mcpServers": { "fortress": { "command": "tilion-mcp" } } }

_{Prefer npx? Use "command": "npx", "args": ["-y", "tilion-mcp"]. Restart Claude, and the fortress tools appear.}

Claude Code (CLI) - one line:

claude mcp add fortress -- tilion-mcp          # or:  claude mcp add fortress -- npx -y tilion-mcp

Cursor (~/.cursor/mcp.json) · Cline / Windsurf (VS Code → MCP servers) - same block:

{ "mcpServers": { "fortress": { "command": "tilion-mcp" } } }

Then just ask your agent - “get the price off this StockX page” - and it calls fetch_protected_page on its own.

What the agent gets

Tools are annotated (reads auto-approve, writes gate), pre-warmed on startup (~100 ms first call), concurrency-safe, and timeout- and SSRF-guarded. A hosted endpoint with residential egress is coming soon.

→ Full 29-tool table, benchmarks, and the agent skill: mcp/

Why patch the engine, not the page

The usual approach patches navigator.webdriver, spoofs the WebGL vendor, and overrides navigator.plugins from script. CreepJS and similar detectors still flag it, and the reason is structural, not one more property left uncovered. A JavaScript spoof is a function standing where a native one belongs. Detectors set the returned value aside and interrogate whether the thing returning it is native:

Realm re-acquisition is the one that defeats every main-world patch. A detector grabs a pristine primitive from another realm and turns it on your function:

const iframe = document.createElement('iframe'); document.body.appendChild(iframe);
const realToString = iframe.contentWindow.Function.prototype.toString;
realToString.call(navigator.__lookupGetter__('vendor')); // returns your source code. Caught.

Your main-world patch lives in a different realm from that iframe. The same trap fires from a Web Worker, a thread your main-thread shim runs beside rather than inside.

Fortress has no such layer. The getter for navigator.vendor is the C++ getter: it reports [native code] because it is native code, identical across every realm. Camoufox puts it well: "there is no JavaScript hijacking to be detected." Fortress applies the same idea to V8 and Blink in place of Gecko.

The three layers of bot detection, and where Fortress fits

Modern anti-bots (Cloudflare, DataDome, Kasada, HUMAN, Akamai) read three structurally different surfaces, in three separate places. One tool rarely fixes all three:

Layer	The tells	Where the fix lives	Fortress
A: driver / binary artifacts	cdc_ ChromeDriver vars, WebDriver protocol surface	Drive raw CDP, skip chromedriver	built to be driven this way
B: CDP side-effects	Runtime.enable leaks via sourceURL + init-script footprints, however clean the binary is	The control / CDP-client layer: hold back Runtime.enable, use Runtime.addBinding + isolated worlds	no leak (verified)
C: fingerprint surface	canvas, WebGL, audio, fonts, navigator, across main frame, iframes, workers	The engine (C++), because JS overrides self-reveal	this is Fortress

Fortress is the Layer-C engine, built to be driven so A and B hold too. The binary alone leaves the CDP channel open. That part is on the control layer, and pretending otherwise is how you get caught.

How Fortress compares

	Stock Playwright	puppeteer-extra-stealth	undetected-chromedriver	Camoufox	CloakBrowser	Fortress
Spoof layer	none	JS injection	CDP/config patch	C++ engine	C++ engine	C++ engine
toString yields [native code]	n/a		n/a
Survives realm re-acquisition (iframe/worker)
No Runtime.enable leak
Engine = Chrome / V8 (majority traffic)				Firefox
Coherent Chromium TLS shape				Firefox
Fully open-source engine					latest major paywalled
Published, auditable patch series	n/a	n/a	n/a		binary only
Reproducible from-source build	n/a	n/a	n/a
States its own limits	n/a	n/a	n/a

Fortress builds on real prior art: fingerprint-chromium, ChromiumFish, and CloakBrowser came first, and commercial vendors (Multilogin, Kameleo, GoLogin, AdsPower, Browserbase, Surfsky) recompile Chromium behind closed source. Most of that work stays closed: the paywalled forks hand you a binary and ask you to trust it, and the vendors keep their patches in-house.

Fortress goes the other way, because a stealth engine only stays useful when the people relying on it can see how it works. Every surface correction lives in patches/ as a small, single-purpose diff you can read in a minute, and the whole engine rebuilds from source with one script. When a detector finds a new tell, you trace the fix, patch it, and send it back. That feedback loop is the point, and it only works while the engine stays open enough to read, extend, and rebuild.

Proof: live-detector results

Reproduce any row with tools/gauntlet.py --bundle ./tilion-fortress. Verified against live detectors; re-run dated in docs/GAUNTLET_RESULTS.md.

Proof: real, unedited screenshots

BrowserScan	CreepJS	Cloudflare

Configure the persona

The binary carries zero brand strings; the launcher applies a coherent default Windows persona. Override any surface with --uxr-* switches, or set TILION_NO_DEFAULTS=1 for a bare launch.

--uxr-platform / --uxr-ua-platform / --uxr-ua-os / --uxr-ua-arch / --uxr-ua-bitness
--uxr-ua-platform-version / --uxr-ua-brand / --uxr-hw-concurrency / --uxr-device-memory
--uxr-webgl-vendor / --uxr-webgl-renderer / --uxr-webgl-fullparams
--uxr-canvas-seed / --uxr-audio-seed / --uxr-timezone / --uxr-languages
--uxr-screen-width / --uxr-screen-height / --uxr-webrtc-policy=disable_non_proxied_udp

Works with your stack

Fortress exposes raw CDP on :9222, so it drops in under anything that speaks Playwright, Puppeteer, or CDP.

from playwright.sync_api import sync_playwright
with sync_playwright() as p:
    browser = p.chromium.connect_over_cdp("http://localhost:9222")   # Fortress under the hood

Build & verify

Reproduce from source

export CHROMIUM_VERSION=$(cat CHROMIUM_VERSION)
build/build.sh                         # depot_tools, sync the tag, apply patches, gn gen, ninja
build/rebase-monthly.sh 152.0.XXXX.0   # bump + 3-way apply + rebuild + gauntlet-gate

Output: out/Fortress/chrome. The fork is 34 small single-surface patches (patches/), so most re-apply cleanly across upstream releases; the gauntlet then gates the release on any regression.

Platform	Status
Linux x64 (native) · Windows x64 (native) · any OS via Docker	shipping
Code-signed installers · macOS .app · linux/arm64	in progress

Verify it's really ours

Fortress ships from four official channels. Treat anything else as untrusted:

Verify a download. Every release ships SHA256SUMS, and the pip/npm SDKs run this for you on install:

BASE=https://github.com/tiliondev/fortress/releases/download/v151.0.7908.0
curl -LO $BASE/tilion-fortress-linux-x64.tar.gz
curl -Ls $BASE/SHA256SUMS | sha256sum -c --ignore-missing     # -> OK

Verify the Docker image by digest (not just the tag):

docker pull tilion/fortress:151.0.7908.0
docker inspect --format '{{index .RepoDigests 0}}' tilion/fortress:151.0.7908.0
# compare the printed sha256:... against the digest in the GitHub Release notes

Or trust nothing and rebuild it. The whole fork is 34 readable patches in patches/; build/build.sh reproduces the binary from Chromium source, so you can diff what you built against what we ship.

Reference

patches/     34 per-surface C++ patches (+ series), the source of truth for the fork
build/       args.gn, build.sh, apply-patches.sh, rebase-monthly.sh, windows/, macos/
packaging/   tilion launcher, fonts.conf, Dockerfile, .deb + bundle builders
fonts/       33 metric-compatible Windows-named fonts (incl. color emoji)
sdk/         python + node (tilion-fortress) prebuilt-binary SDKs
tools/       gauntlet.py, the CreepJS / Sannysoft / BrowserScan CI gate
docs/        GAUNTLET_RESULTS, BUILD_NATIVE, BENCHMARK

What's next