Stealth

Stealth makes a BrowserHive session report what a real Chrome on your machine would report, and optionally makes input look hand-made. It is not invisibility. This page says what it does, what it does not do, and where the ceilings are.

The principle: assert nothing rather than assert something wrong. BrowserHive never invents an operating system, GPU, timezone or location. Everything it presents is derived from the real host.

Levels

--stealth	What you get
off	Stock Playwright Chromium. navigator.webdriver is true. No identity override.
standard (default)	The full Chromium binary in new-headless mode, the Patchright driver when installed, automation flags removed, and a coherent identity applied through the DevTools protocol.
max	standard plus a display fingerprint (fingerprint defaults to true).

Related keys:

Key	Default	Effect
--stealthDriver	auto	auto uses Patchright when installed, else Playwright. patchright requires it (startup fails with BROWSER_NOT_INSTALLED if missing). playwright never uses it.
--fingerprint	true only with max	Coherent screen and window geometry per session. Requires standard or max.
--humanize	false	Human-like pointer paths and typing rhythm. Requires standard or max.
--defaultHeadless	true	Default for launch_session headless.
--defaultChannel	chromium	Default browser: chromium, chrome or edge.

An agent can override stealth, fingerprint, humanize, headless and channel per session in launch_session. The dashboard’s Identity tab shows what each session actually presents, and list_sessions / session_info return it as identity.

What standard does

• Real browser binary. chromium runs the full Chromium build, never the stripped headless shell. That restores window.chrome, plugins, MIME types, the PDF viewer flag and hardware WebGL.
• Automation signals removed. navigator.webdriver is false; the --enable-automation switch is not passed.
• Patchright (when installed by browserhive init) patches the remaining automation leaks at launch. evaluate still runs in the page’s main world.
• One coherent identity, set through the DevTools protocol on every page, including new tabs and popups before their first request:
  • User agent: the real one, with HeadlessChrome rewritten to Chrome.
  • Client hints: brands Chromium and Google Chrome with the real version, platform and architecture from the host, platform version from the OS release.
  • Accept-Language from the host locale (en-CA → en-CA,en), and navigator.deviceMemory when the browser would report none.
• Locale and timezone from the host (LC_ALL, LANG, the system timezone). No coordinates are ever set.
• set_extra_http_headers refuses to change user-agent, accept-language and sec-ch-ua* on stealth sessions, so the identity stays consistent.

What fingerprint adds

A believable screen for headless sessions: a display size from a catalogue that matches the host OS family (for example 1512×982 at 2× on macOS, 1920×1080 on Windows and Linux; never Playwright’s default 1280×720), with a window size and position derived from it so that innerHeight < outerHeight ≤ availHeight ≤ screen.height always holds. The patched getters report themselves as native code.

It is seeded per session. A profile saved with save_full_profile keeps its seed, so restoring it brings back the same screen with the same cookies. Hardware concurrency, WebGL vendor and renderer, canvas, audio and fonts are left native on purpose: they are cross-checkable against the real GPU.

Downgrades, each recorded as a session warning:

• A headed session gets locale and timezone only, because its window is really on screen.
• A caller-supplied viewport keeps the geometry unasserted (VIEWPORT_OVERRIDE_UNASSERTED).
• A proxy passed in launch_options or context_options disables the host locale and timezone, because host values over someone else’s exit IP are worse than none (BYO_PROXY_UNSEEDED).
• A caller-supplied locale or timezoneId is honoured.

If applying the identity fails, the session continues without it and records STEALTH_INIT_FAILED.

What humanize adds

click, hover, type_text, scroll (by offset) and vault typing use curved pointer paths with overshoot, Fitts-law timing, press dwell, and typing with varied intervals, word pauses and occasional corrected typos. It is seeded per session, so each session has one consistent “hand”. Long text (over 400 characters) and calls whose timeout budget is too small fall back to native input, so timeouts keep working. fill, select_option and drag_and_drop stay native.

Launch-argument guard

To protect isolation, launch_options.args may not contain --user-data-dir, --profile-directory, --disk-cache-dir, --no-sandbox, --disable-setuid-sandbox, --disable-web-security, --disable-site-isolation-trials, --disable-features, --single-process, --no-zygote or the remote-debugging switches. chromiumSandbox: false, env, downloadsPath and recordVideo are refused too. Violations fail with UNSAFE_LAUNCH_ARG. An executablePath override is allowed but disables channel routing (EXECUTABLE_PATH_OVERRIDE).

Proxies

There is no managed proxy support. Bring your own through Playwright’s options:

launch_session({
  "slug": "geo",
  "launch_options": { "proxy": { "server": "http://proxy.example:3128", "username": "u", "password": "p" } }
})

Loopback and private network ranges are always bypassed so local tooling never goes through the proxy. The session records a proxy_label (never credentials). Chromium’s raw proxy switches are also accepted in args. A managed pool with rotation and exit-IP geolocation is planned; the configuration key proxy is reserved for it and rejected today.

Ceilings

These are known and documented, not bugs:

• TLS fingerprints (JA3/JA4) cannot be changed through Playwright. They are already close to Chrome’s.
• Out-of-process iframes are not covered by the user-agent override; cross-origin frames may report the raw user agent.
• The hardest bot checks (for example Cloudflare Turnstile in strict mode) can still detect DevTools-protocol automation and synthetic input. Use human takeover for them.
• Canvas, audio and font entropy are the host’s own: a stable identity tied to your machine, not a rotating one.
• GREASE brand and platform version are plausible values, not byte-exact copies of the installed Chrome.
• WebAuthn and passkeys cannot be replayed from saved state.
• Firefox and WebKit are not supported.

Stealth is a capability for legitimate automation of sites you are allowed to use. Respect their terms.