Stealth Mode

Stealth mode, in the context of web automation, refers to a set of patches applied to headless browsers to hide the fact that they are automated. Vanilla Puppeteer or Playwright sessions expose obvious tells: `navigator.webdriver === true`, missing `chrome` runtime properties, suspicious window dimensions, predictable plugin lists, and broken WebGL rendering. Anti-bot systems probe these specifically. Stealth plugins like puppeteer-extra-plugin-stealth and the equivalents for Playwright patch each known tell so the browser fingerprint resembles a real user's.

The cat-and-mouse dynamic is constant. Every few months, anti-bot vendors discover a new tell that stealth plugins do not yet patch, and shortly after the open-source community ships an update. Managed browser infrastructure providers (Browserbase, Steel.dev, Anchor Browser, Hyperbrowser) market stealth as a continuous capability – they update their browser images frequently and run automated fingerprint tests against major anti-bot vendors so customers do not have to.

For AI builders, the practical advice is the same as with broader anti-bot evasion: do not maintain stealth in-house unless you must. Pay a vendor whose business model depends on staying ahead of detection. The savings in engineering time more than pay for the per-session cost.