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What is fortress?

tiliondev/fortress — explained in plain English

Analysis updated 2026-05-18

392PythonAudience · developerComplexity · 4/5LicenseSetup · easy

In one sentence

A modified Chromium browser engine that hides automation fingerprints inside the C++ code itself, so Playwright and Puppeteer scripts appear as ordinary Chrome to bot detectors.

Mindmap

mindmap
  root((Fortress))
    What it does
      Stealth Chromium
      Engine level patches
      Bot detection bypass
    Tech stack
      Chromium
      C++
      Playwright
    Features
      CDP compatible
      Tunable persona
      MCP tools
    Use cases
      Automation scripts
      Detector testing
      Agent browsing

Code map

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What do people build with it?

USE CASE 1

Run existing Playwright or Puppeteer automation through a browser that resists bot detection.

USE CASE 2

Test how your own website's bot detection holds up against a stealthy real Chromium build.

USE CASE 3

Give an AI agent a set of stealth browsing tools through the included MCP server.

USE CASE 4

Adjust the simulated browser identity, like timezone, screen, and keyboard layout, for consistency.

What is it built with?

PythonChromiumC++PlaywrightPuppeteer

How does it compare?

tiliondev/fortressfacebookresearch/spdlkarpathy/covid-sanity
Stars392393393
LanguagePythonPythonPython
Last pushed2026-06-252020-05-03
MaintenanceActiveDormant
Setup difficultyeasymoderatemoderate
Complexity4/53/53/5
Audiencedeveloperdeveloperresearcher

Figures from each repo's GitHub metadata at analysis time.

How do you get it running?

Difficulty · easy Time to first run · 5min

Installable via pip, npm, or Docker, existing Playwright or Puppeteer code needs only a small change to point at it.

Use freely for any purpose, including commercial use, as long as you keep the copyright notice (BSD 3-Clause license).

So what is it?

Fortress is a modified version of the Chromium browser engine, the same engine that powers Google Chrome, built so that automated browser tools do not get flagged as bots. Sites that try to detect automation usually inspect small details of the browser, such as how it draws graphics, reports its fonts, or answers certain JavaScript questions, looking for signs that a script rather than a person is in control. Instead of patching those answers with extra JavaScript sitting on top of the page, which a determined detector can still catch, Fortress corrects those answers directly inside Chromium's own C++ code, so the browser looks like an ordinary Chrome install from every angle a page can check. It runs as a normal browser binary that speaks the Chrome DevTools Protocol, the same interface tools like Playwright and Puppeteer already use to control a browser. That means existing automation code generally keeps working with only a small change: point it at Fortress instead of a regular browser. The README reports that it passes several public bot detection tests, including CreepJS, Sannysoft, and BrowserScan, and clears a live Cloudflare challenge in a recorded demonstration. It also offers tunable settings for things like screen size, timezone, and keyboard layout so the simulated browser identity stays internally consistent. Beyond the raw browser engine, the project includes an add on called the Fortress MCP, currently in beta, which exposes about 29 browsing related tools that an AI agent can call directly. The engine's source patches are kept small and separated by purpose so each one can be read individually, and the project rebuilds from the upstream Chromium project on a monthly basis. It can be installed through pip, npm, or Docker. Fortress is released under the BSD 3 Clause license, a permissive license similar to MIT that allows free use including commercial use, provided the copyright notice is kept and the project's name is not used to promote derived products without permission. It has 392 stars. The full README is longer than what was shown.

Copy-paste prompts

Prompt 1
Help me swap my existing Playwright script to connect to Fortress over CDP instead of a regular browser.
Prompt 2
Explain why Fortress patches the Chromium engine itself instead of injecting JavaScript to hide automation.
Prompt 3
Show me how to configure Fortress's persona settings like timezone and screen size.
Prompt 4
Walk me through setting up the Fortress MCP server so an AI agent can browse through it.

Frequently asked questions

What is fortress?

A modified Chromium browser engine that hides automation fingerprints inside the C++ code itself, so Playwright and Puppeteer scripts appear as ordinary Chrome to bot detectors.

What language is fortress written in?

Mainly Python. The stack also includes Python, Chromium, C++.

What license does fortress use?

Use freely for any purpose, including commercial use, as long as you keep the copyright notice (BSD 3-Clause license).

How hard is fortress to set up?

Setup difficulty is rated easy, with roughly 5min to a first successful run.

Who is fortress for?

Mainly developer.

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