The open-source Fortress alternative
Fortress is an engine-level stealth Chromium you drive over CDP, source-available since v3 and paid in production above a funding or revenue threshold. Clearcote is engine-level Chromium too, with a BSD-3 open build, SDKs that return Playwright objects, and one price whatever your company's funding or revenue.
What is Fortress?
Fortress, by Tilion Inc., is a Chromium fork for scrapers and browser agents that patches fingerprint surfaces in Chromium's C++. You start the engine from its Python or Node package, its tilion launcher or its Docker image, and connect Playwright, Puppeteer, browser-use or another client over CDP; an MCP server (marked beta) gives AI agents the same browser as tools. Each launch gets a fresh persona unless you pin the machine with --uxr-seed (or TILION_SEED) for a sticky account identity; canvas, WebGL-readback and audio noise is drawn fresh on every launch by design. Version 3 (v153.0.8010.36, released on 30 September 2026) is based on Chromium 153, with release files for Windows x64, Linux x64, arm64, armhf and x86, and macOS arm64.
Until 30 September 2026 Fortress was BSD-3. From v3 on it is under the Fortress Source Available License 1.1, which states that it is not an open-source license. Anyone may read, modify and redistribute the code and use it for non-production work at any size. Production use is free for personal, non-commercial use and for organisations under US$500,000 in cumulative funding with no more than US$300,000 in annual recurring revenue; an organisation above either line needs one subscription, listed at US$2,000 a month in three-month terms, which covers the whole organisation with no limit on machines or browsers. The earlier BSD releases (up to Chromium 151) keep their BSD licence. The full v3 engine is unlocked by a licence key from a free sign-in, checked on the machine rather than online; without a key the binary runs the public first-generation engine. The repository publishes that first-generation series as 35 patches, and the README describes the full fork as 81.
Sources, checked on 6 October 2026: the licence and production terms from the repository's LICENSE, LICENSE-BSD-LEGACY and SUBSCRIPTION-TERMS.md and the pricing page; the Chromium version, release date and platforms from the v153.0.8010.36 release; the SDK languages, the MCP server, the key behaviour and the patch counts from the README and the repository's patches/ folder; the identity and noise behaviour from docs/UXR_CONFIG.md.
Clearcote vs Fortress
| Feature | Clearcote | Fortress |
|---|---|---|
| Chromium version | Chromium 154 (latest build) | Chromium 153 (v3, 30 September 2026) |
| Licence | Open build and SDKs BSD-3; the latest build adds private patches | Fortress Source Available License 1.1 since v3; earlier releases BSD-3 |
| Cost below Fortress's thresholds | Open build free; latest build free with GitHub (one browser at a time); Pro $49/mo for more | Free, production included, with no browser limit: personal non-commercial use, or an organisation under US$500,000 funding and up to US$300,000 ARR |
| Cost above Fortress's thresholds | Open build free at any size; Pro $49/mo, up to 250 browsers at once | US$2,000/month per organisation for production use, in three-month terms |
| Platforms | Windows x64, Linux x64 (Docker image for x64) | Windows x64; Linux x64, arm64, armhf and x86; macOS arm64 |
| SDKs | Python, Node and .NET, returning Playwright objects or a CDP endpoint | Python and Node, starting the engine on a CDP endpoint |
| Licence key | None for the open build; the latest build checks out a lease from the licence API at launch | Needed for the full v3 engine; free sign-in, checked offline |
| CDP endpoint / Docker / MCP | Yes: serve(), Docker image, MCP server | Yes: CDP launcher, Docker image, MCP server (beta) |
| Identity across launches | One seed reproduces the whole persona, per-site canvas and WebGL noise included | Fresh persona per launch; --uxr-seed pins the machine, while canvas and audio noise stay fresh by design |
Comparison compiled October 2026. Fortress is source-available since v3; earlier releases bsd-3; details change — check its project for the latest.
Why teams pick Clearcote
An open build under BSD-3
Clearcote's open build and its SDKs are BSD-3 and free in production for any company, with every patch readable and the build reproducible. The latest build adds private patches and is free with GitHub for one browser at a time.
One price at any size
Pro is $49 a month whatever your funding or revenue, so there's no threshold to track as a company grows.
Playwright objects, not only a CDP URL
launch() returns a Playwright Browser in Python, Node and .NET with the persona and proxy already applied, and serve() gives the same engine as a CDP endpoint when a framework needs one.
One seed, the whole identity
A fingerprint seed reproduces the whole persona on every launch, per-site canvas and WebGL noise included, so a returning account looks the same each session. Fortress pins the machine with --uxr-seed but draws canvas and audio noise fresh on every launch, by design.
When Fortress might be the better pick
- You need ARM or macOS. Fortress v3 has release files for Linux arm64, armhf and x86 and for macOS arm64; Clearcote ships Windows x64 and Linux x64 only.
- You use it personally and non-commercially, or your organisation is under the funding and revenue thresholds, and you want the full engine in production at no cost with no browser limit.
- You need to run without a licence server: Fortress checks its key on the machine, while Clearcote's latest build checks out a lease from the licence API at launch (Clearcote's open build needs no key or account).
- You want render noise that cannot link one session to the next: Fortress draws canvas and audio noise fresh on every launch, even when
--uxr-seedkeeps the same machine. - Fortress is a serious engine-level project. If its licence terms fit your organisation, it's a reasonable choice.
FAQ
Is Fortress still open source?
Not since 30 September 2026. Releases from v3 on use the Fortress Source Available License 1.1, which describes itself as source-available rather than open source: free to read, modify and redistribute, free for non-production use, and free in production below the funding and revenue thresholds. Releases before that date (up to Chromium 151) keep their BSD-3 licence. Clearcote's open build and SDKs are BSD-3.
How much does Fortress cost?
It's free for non-production use at any size, and free in production for personal, non-commercial use and for organisations under US$500,000 in cumulative funding with no more than US$300,000 in annual recurring revenue. Above either line, production use needs one subscription per organisation, listed at US$2,000 a month in three-month terms. Clearcote's open build is free at any size, the latest build is free with GitHub for one browser at a time, and Pro is $49 a month.
Which Chromium version is Fortress on?
v3, released on 30 September 2026, is Chromium 153 (153.0.8010.36). Clearcote's latest build is Chromium 154. Both projects publish new majors on their releases pages.
Can I move a Fortress CDP setup to Clearcote?
Yes. Both serve a CDP endpoint, so the code that connects to it stays the same and only the way the browser starts changes. The migration guide covers serve(), clearcote serve and the Docker image.
Related reading
Try the open-source Chromium alternative
Free and open source, a drop-in for Playwright & Puppeteer, coherent down to the TLS handshake.
Free for one browser with GitHub. No card.