Fortress is an innovative open-source stealth browser engine developed by the Tilion team, first released to the public in July 2026. This tool was created with a clear purpose: to address the problem of modern AI agents and web data scrapers being indiscriminately blocked by sophisticated bot detection systems. To eliminate inconsistencies that arise when conventional automated browsers communicate with web servers, Fortress employs an architecture that goes beyond simply manipulating JavaScript-level variables. It deeply modifies the C++ source code of Chromium. It applies in-tree patches, compiling them directly within the source code tree, even down to the lowest-level specifications of the rendering engine Blink, the JavaScript engine V8, and the secure cryptographic communication library BoringSSL. Just as a large language model like GPT generates natural-sounding sentences to realistically mimic human conversation, Fortress organically unifies CPU specifications, graphics processing unit (GPU) driver acceleration information, system font lists, and audio context parameters to perfectly emulate the typical Chrome browser environment of a regular Windows user. In the field of web automation, previously widely used proxy script-based tools like Puppeteer-stealth or Playwright-stealth employed a temporary fix by overwriting JavaScript global objects (e.g., navigator) within the browser at runtime (Monkey Patching). However, recent intelligent bot detection solutions easily detect the presence of these stealth layers by analyzing the JavaScript execution context when a web page is initially loaded. For example, when a string conversion function (toString()) is called on an overwritten function object, the browser engine's pure machine code execution, indicated by native code ([native code]), is not output, and traces of manipulation are detected. Alternatively, the overwriting is bypassed when the prototype object is re-called within a sub-frame (iframe) isolated by a security sandbox or within a background web worker, exposing the original headless indicators. Fortress strictly adheres to the principle of Realm Invariance, ensuring that all contexts within the virtualized environment, and even the network shape of encrypted packets (JA3/JA4 TLS), perfectly match their original identity. This is a crucial differentiator that elevates the detection evasion system to the next level. From a researcher's perspective, Fortress can function as a critical infrastructure responsible for the survival of data acquisition pipelines. For example, public and private servers that provide access to global medical and compound registry websites or genomic sequence analysis tools have implemented strict anti-bot solutions, such as Akamai Bot Manager or Cloudflare Turnstile, to protect server resources, making it difficult for conventional crawlers to even access the first page. Researchers can simply modify a single line of code in their existing Playwright or Puppeteer source code, removing the option to directly execute the Chrome browser and connecting to the Chrome DevTools Protocol (CDP) port on a local or remote machine where Fortress is running. Because the virtual keyboard AZERTY/QWERTY layout, tailored to the locale settings, the media device list that matches the device resolution, and the actual ANGLE graphics driver hardware acceleration backend operate harmoniously, the security filter completely trusts this as pure traffic from a legitimate researcher directly accessing the site with a Chrome browser and manipulating the mouse and keyboard, allowing all access immediately. Perfect integration with the emerging AI web agent ecosystem is also one of Fortress's key strengths. When LLM-based web automation agents, such as Browser-use, Crawl4AI, and LangChain, dynamically navigate elements on a web page and perform tasks such as signing up or retrieving data, Fortress effectively eliminates the problem of agent loops collapsing due to obstacles such as CAPTCHAs. With 34 precise C++ patches, it guarantees verified coherence, providing a robust foundation for AI agents to navigate complex multi-step business logic without being blocked by detection servers, allowing them to complete uninterrupted navigation to their destination.

Fortress is an innovative open-source stealth browser engine developed by the Tilion team, which was first released to the public in July 2026. This tool was created with the clear objective of addressing the problem where modern AI agents and web data scrapers are indiscriminately blocked by sophisticated bot detection systems. To eliminate inconsistencies that occur when conventional automated browsers communicate with web servers, Fortress adopts an architecture that goes beyond simply manipulating JavaScript-level variables and instead deeply modifies the C++ source code of Chromium.