veilbrowser
This MCP server exposes a stealth Chrome browser automation toolset for AI agents — navigation, accessibility-snapshot interaction, human-like input, fingerprint control, and page inspection.
Navigate, reload, go back/forward, and wait for load/network idle.
Snapshot the accessibility tree into numbered refs, then click, fill, type, select, press keys, drag, scroll, or click by coordinates.
Read element text/attributes, take screenshots (viewport/element/clip/full page), evaluate JS, and print pages to PDF.
Apply coherent fingerprints/presets, set UA/viewport, block resources, and use private-network protections via the underlying project.
Manage cookies, upload files directly or via file pickers, wait for JS/selectors, and handle FedCM/Google sign-in flows.
Work with cross-origin iframes, close the browser, and launch/attach to Chrome as needed.
Enables automated browsing of Cloudflare-protected sites by driving a real Chrome browser through their JS challenges.
Provides stealth automation for Google properties, including completing 'Sign in with Google' (FedCM) flows to access Google SSO apps.
Allows automated interaction with Instagram using an undetectable real Chrome session.
Supports automation of Meta-owned sites with an established browser profile that avoids session-scored bot detection.
Enables automated browsing and interaction with Reddit in a real Chrome session, bypassing bot checks.
Provides automation for TikTok using a trusted Chrome profile, avoiding the site's session-based bot detection.
Veil
A stealth automation runtime for AI agents. Drives real Chrome over raw CDP — no Playwright, no Puppeteer, no WebDriver, zero runtime dependencies.
Built by HamTek — we build production-grade AI agents; veil is the proof.

Veil driving real Chrome: bot.sannysoft.com all-green, then straight through Cloudflare's JS challenge — no patches, no plugins.
To Instagram, Google, Reddit, Cloudflare — Veil is Chrome. Same binary, same TLS, same JS engine, same canvas/WebGL/font fingerprint a human's browser has. We don't reimplement the browser (that's Chromium's 20-year, 1000-engineer job, and a hand-rolled engine is easier to fingerprint, not harder). We replace the part that gets you caught: the automation layer.
Why not Playwright / Puppeteer?
They're powerful and great for scripted QA. For agents on hostile sites they have three structural problems:
Problem | Playwright/Puppeteer | Veil |
Detectable |
| webdriver scrubbed, no automation switches, no |
Robotic input | instant teleport clicks, fixed-cadence typing → behavioural detection | curved Bézier mouse paths, eased timing, human keystroke cadence |
Brittle for agents | CSS/XPath selectors that break constantly | accessibility-tree snapshot → stable integer |
Veil is dependency-free — Node 24 / Bun ship a global WebSocket, so the entire
CDP transport is ~120 lines we own. Nothing to patch, nothing to leak.
Related MCP server: Antigravity Browser Operator
How Veil compares (honest)
The "real Chrome over raw CDP" idea isn't new — Python's nodriver
pioneered it, and Camoufox (a C++-patched Firefox) scores even
better on pure stealth. Veil isn't claiming to out-stealth them. Its wedge is where it
lives and how agents use it:
TypeScript-native. The JS/TS agent ecosystem (Vercel AI SDK, LangChain.js, MCP) has no strong raw-CDP stealth driver — it's stuck on Playwright + stealth plugins, or shelling out to Python
nodriver. Veil is that missing piece.MCP-native. Ships an MCP server, so any agent gets stealth browsing as tools with zero glue.
Agent-first, not scraper-first. Accessibility-tree refs and human input are built for an LLM driving the browser, not for a scraping script.
Does two things the others don't. Drives the native "Sign in with Google" (FedCM) account chooser over CDP — agents are otherwise walled out of Google-SSO apps entirely — and blocks visited sites from port-scanning your localhost/LAN (on by default). Neither
nodriver, Camoufox, nor Playwright-stealth does either.
Two more that get raised, and where they actually land
Both of these came up when Veil was posted publicly, so they belong here rather than in a comment thread.
Patchright (Python + Node) — a patched, drop-in Playwright replacement. It fixes Playwright's launch-flag and JS-surface leaks: adds
--disable-blink-features=AutomationControlled, drops--enable-automation, correctsnavigator.webdriverand theHeadlessChromeUA. Chromium only. If you already have Playwright code and want it less detectable, this is the lowest-friction option and you should probably use it — it's a dependency swap, not a rewrite. Where it differs: it is still Playwright underneath, so it launches its own browser and therefore hits the sameuser-data-dirlock — it cannot attach to a profile you're already signed into. Attaching isn't a stealth patch, it's a different architecture, and it's the thing that actually gets you past session-scored sites.Claude for Chrome — an extension running inside your own browser. It shares Veil's core insight (use the real browser, inherit the real session) and, being a genuine extension rather than automation, it isn't fighting bot checks at all. If you want a human-in-the-loop assistant in your browser, it's a better fit than a library. Where it differs: it isn't programmable. You can't call it from a script, wire it into CI, run it headless on a server, expose it as MCP tools to your own agent, or control the fingerprint. Veil is a library your code drives; that's a different job, not a better one.
If you're in Python and just want raw stealth, use nodriver or Camoufox — they're great. If
you have Playwright code already, try Patchright first. If you want an assistant in your own
browser, use Claude for Chrome. Veil is for TypeScript agents and MCP hosts that need to
drive a browser programmatically — and, uniquely among these, one you're already signed into.
Quick start
Prerequisites: Chrome/Chromium on PATH (or VEIL_CHROME=/path/to/chrome), and Bun.
bun install
bun run examples/selftest.ts # launches real Chrome, runs the full chainIn your own project — bun add @achamm/veilbrowser (or npm install @achamm/veilbrowser):
import { Browser } from "@achamm/veilbrowser";
const browser = await Browser.launch({ headless: false }); // headful = stealthiest
const page = await browser.newPage();
await page.goto("https://example.com");
// Accessibility-tree snapshot → stable integer refs (no selectors).
const snap = await page.snapshot();
console.log(snap.text);
// [1] textbox "Search"
// [2] button "Sign in"
await page.fill(1, "hello"); // act by ref — human typing, jittered timing
await page.click(2); // curved Bézier mouse path, real CDP input
const png = await page.screenshot(); // PNG buffer for a vision model
await browser.close();Drive a browser you're already signed into
Chrome locks a user-data-dir. The one profile holding your real logged-in sessions
therefore cannot be opened by a second Chrome, which is why launching your own browser
always gets you a fresh, logged-out, brand-new-looking session — the shape that gets
challenged. Browser.connect() attaches to a browser that is already running instead:
# start Chrome yourself, with the profile that has your sessions in it
google-chrome --remote-debugging-port=9222 --user-data-dir=~/.config/agent-profileimport { Browser } from "@achamm/veilbrowser";
const browser = await Browser.connect("127.0.0.1:9222"); // ws:// URL, http:// origin, or host:port
const [page] = await browser.pages(); // the tab that's already open
await page.goto("https://example.com");
await browser.close(); // DETACHES ONLY — never kills a browser it didn't startThis matters because Google, Reddit, Meta and TikTok score the session, not the IP: an established profile passes where a fresh one hits a wall.
⚠️ The profile becomes part of your agent's security boundary
This is the real cost of attaching, and it is worth stating plainly rather than leaving in the fine print. Whatever that Chrome profile is signed into, the agent can reach. Point it at your everyday browser and an agent that wanders — or a prompt-injected page telling it to — has your email, your bank, your admin panels. There is no per-site sandbox inside a profile; a cookie jar is all-or-nothing.
Use a dedicated profile signed into only what the task needs. A separate
--user-data-dirper agent, logged into the two or three sites it actually works with, keeps the blast radius equal to those sites instead of your whole digital life. The private-network block is on by default for a related reason (a page cannot port-scan your LAN), but it does nothing about credentials that are legitimately in the jar.Credit to
u/zhonglinon r/AI_Agents for naming this precisely: reusing an authenticated browser solves session continuity and moves the profile inside the agent's trust boundary.A fingerprint is deliberately not re-applied to an attached page — changing
navigatorproperties under a document the site has already fingerprinted is more detectable than leaving them alone.
Attach safety
Attaching puts the whole profile inside the agent's trust boundary, and the origin allowlist
is narrower than it sounds: it gates document navigation by the library (allowOrigins)
and nothing else (not fetch, images, popups, eval, uploads, downloads or cookie reads).
The MCP server does not apply the allowlist on this version. See
docs/SECURITY.md for the threat model, a per-control table with the test
behind each enforced row, and the attach-safety env vars.
Python
There is a Python front end in python/ with the same core API:
pip install git+https://github.com/acunningham-ship-it/veilbrowser.git#subdirectory=pythonimport asyncio
from veilbrowser import Browser, Fingerprint
async def main():
async with await Browser.launch(fingerprint=Fingerprint.preset("windows-chrome")) as b:
page = await b.new_page()
await page.goto("https://example.com")
print(await page.title())
asyncio.run(main())The stealth layer has one implementation, not two. The injected script, the launch
flags, the profile identities and the keystroke table are generated from this
TypeScript source into python/veilbrowser/_assets/ by tools-gen-python-assets.ts,
and tests/python-parity.test.ts fails the build if Python's assembled script differs
from the TypeScript one by a single byte. That matters because a drifted stealth patch
does not fail loudly — one front end simply becomes detectable while all of its own
tests stay green. See python/README.md for the API and for what is
deliberately not ported.
How the stealth works
Launch (
launcher.ts) — a real Chrome with the flags a normal profile uses, minus the automation switches Playwright adds.--disable-blink-features=AutomationControlledflipsnavigator.webdrivertofalseat the engine level. PersistentuserDataDirso the profile looks used (history, cookies), not freshly minted.Transport (
cdp.ts) — raw WebSocket, flat session mode. We never callRuntime.enable— that command is a primary CDP detection vector.Runtime.evaluateworks without it.Page patch (
stealth.ts) — injected viaaddScriptToEvaluateOnNewDocumentbefore any site code, on every frame. Every patch is self-gating: it fires only when a value is genuinely anomalous (a stripped/headless env leakedwebdriver === true, 0 plugins, an emptylanguages, or a missingwindow.chrome), and is a no-op on a healthy real Chrome. That's the whole default surface — awebdriver/window.chrome/plugins/languagesbackfill, nothing more. It deliberately does not touchpermissions.query: a patchedpermissions.queryis itself a signature deep fingerprinters score as "stealth detected". WebGL-vendor spoofing (and the native-lookingtoString()mask that hides it) is opt-in viamaskWebgl— off by default, used only to disguise SwiftShader on GPU-less hosts; with a real GPU the authentic vendor is left untouched. Kept deliberately small; over-patching is its own fingerprint.UA / client hints (
page.ts) — strips theHeadlessChrometoken from the UA and theSec-CH-UAbrand headers.Human input (
human.ts) — seedable PRNG drives curved mouse paths and jittered keystroke timing.
Coherent fingerprints / profiles
By default Veil ships your real Chrome fingerprint — the strongest identity there
is, because nothing is spoofed. When you instead need to present a specific
identity (a Windows profile from a Linux server, a fixed profile across a pool),
apply a Fingerprint. The design rule is coherence, not spoof-count: a
half-spoofed profile is worse than none — if the UA says Windows but the client
hints, navigator.platform, or WebGL vendor disagree, that contradiction is itself
a detection signal. So a Fingerprint is applied as one internally-consistent set,
and every derived value (client-hint platform, brand versions, Accept-Language) is
computed from the profile so nothing can drift out of agreement.
import { Browser, type Fingerprint } from "@achamm/veilbrowser";
const fp: Fingerprint = {
userAgent: "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 " +
"(KHTML, like Gecko) Chrome/131.0.6778.86 Safari/537.36",
platform: "Win32", platformVersion: "15.0.0", architecture: "x86", model: "", mobile: false,
hardwareConcurrency: 16, deviceMemory: 8, languages: ["en-US", "en"],
screen: { width: 2560, height: 1440, availWidth: 2560, availHeight: 1400, colorDepth: 24 },
devicePixelRatio: 1,
webglVendor: "Google Inc. (NVIDIA)",
webglRenderer: "ANGLE (NVIDIA, NVIDIA GeForce RTX 3060 Direct3D11 vs_5_0 ps_5_0, D3D11)",
timezone: "America/New_York", locale: "en-US", seed: 12345,
};
const browser = await Browser.launch({ headless: false, fingerprint: fp }); // applied to every page
// or at runtime, before the first navigation:
await page.applyFingerprint(fp);Don't want to hand-build one? Use a preset or a self-consistent random profile:
import { Browser, Fingerprint, PRESETS } from "@achamm/veilbrowser";
await Browser.launch({ fingerprint: PRESETS["mac-chrome"] }); // windows/mac/linux/android-chrome
await Browser.launch({ fingerprint: Fingerprint.random() }); // fresh coherent identity
await Browser.launch({ fingerprint: Fingerprint.random(42) }); // deterministic given a seedFingerprint.random(seed?) picks a platform first, then derives a matching UA,
client hints, WebGL, screen and timezone — so a random profile is as internally
consistent as a preset. Each preset is a real Chrome-131 identity for its OS (an
Apple-Silicon Mac still reports the frozen Intel Mac OS X 10_15_7 UA + MacIntel
platform with an arm architecture and an Apple Metal renderer — exactly as a real
one does).
How it's applied (two layers). The bulk goes through Chrome itself — UA +
the full userAgentMetadata client hints + the legacy navigator.platform, the
screen size + devicePixelRatio, and the timezone / locale / geolocation —
all via CDP Emulation.*. These are set by the browser, so there is no JS getter
to unmask — the strongest kind of spoof, and they resolve natively
(Intl.DateTimeFormat().resolvedOptions().timeZone, navigator.language,
navigator.geolocation). A US profile should carry a US timezone/locale (and
optional US coordinates) — a region that disagrees with the UA is a contradiction
detectors score. Only
the values CDP can't set are injected as page-level overrides — hardwareConcurrency,
deviceMemory, languages, screen.avail*/colour depth, the WebGL vendor/renderer
(the two UNMASKED_* parameters), and deterministic canvas + audio noise. Every
one is defined on the prototype (inherited, so no own-property tell) with its
toString() masked to [native code] by a single Function.prototype.toString proxy
that hides itself and leaves genuine native/user functions untouched — the same
discipline the base stealth uses.
The canvas/audio noise is seeded, not random per call: repeated reads of the same
canvas or audio buffer return identical bytes (a per-call random is itself a tell),
while a different seed yields a different — but equally stable — hash. So a profile
carries its own consistent canvas/audio fingerprint instead of leaking the host's.
Honest scope: this is coherent fingerprint control, not a magic bullet. It lets
you present a consistent identity; it does not by itself defeat any particular hard
target. navigator.oscpu is deliberately left unset (it's Firefox-only — a Chrome
profile exposing it would be an anomaly); screen.colorDepth follows the profile but
the rendered pixels still come from the host GPU, so keep webglVendor/webglRenderer
plausible for the platform you're claiming; and WebGL-canvas read-back (toDataURL on
a WebGL canvas) is left to the vendor override, not noised.
Agent tooling (the other half of the product)
The selling point isn't only stealth — it's that agents drive it well:
snapshot()returns the page as a flat numbered index from the accessibility tree (the semantic layer screen readers use). The #1 cause of agent breakage — guessed CSS/XPath selectors — is gone. The agent acts on a stableref. Arefis an identity, not a position: an element keeps its number for as long as the document lives, so a number is never reused for a different element. Refs are1..Non the first snapshot and may then develop gaps (something was removed) or run out of order (something was inserted above older elements). That is deliberate — renumbering per snapshot means a rememberedrefcan actuate the wrong element and still report success. Here a stale ref is either still correct, or a clear error.screenshot()returns a PNG buffer, ready for vision grounding — the viewport, the whole{fullPage}, a single element{ref}, or an explicit{clip}rectangle.click/fill/typedrive real CDP input with human dynamics.waitFor(expr)replaces flaky fixed sleeps — and, likeevaluate(), is timeout-bounded, so a wedged page rejects cleanly instead of hanging the agent.goto()returns{ status, ok }for the main response, so callers can detect a 4xx/5xx wall instead of only seeing a rendered error page.blockResources(types, {urls})drops image/font/media/etc. and URL-matched requests — a big speed and footprint win for scraping (shares one Fetch handler with the private-network guard, so both are active at once).
Federated sign-in (FedCM)
"Sign in with Google" one-tap and the newer navigator.credentials.get({identity})
flows render their account chooser as native browser UI — the button is a
cross-origin IdP iframe and the chooser is browser chrome, so no synthetic click can
reach either. That's a wall for agents logging into Google-SSO apps. Veil drives it
over CDP's FedCM domain instead:
// Passive / one-tap (fires on load once you're signed in to the IdP):
await page.enableFedCm(); // autoSelectFirst — picks account 0 for you
await page.goto("https://app.example.com/");
await page.waitForFedCmDialog(); // chooser intercepted + auto-selected
await page.disableFedCm();
// Active "Sign in with Google" button, one call:
const account = await page.signInWithFedCm({ triggerRef: btn.ref });enableFedCm also resetCooldowns (Chrome silently suppresses the dialog after
repeated dismissals) and binds account selection to the page's own CDP session — pick
the wrong target and the dialog, plus the page's credentials.get(), hangs forever.
Enable it on demand, right before the sign-in: turning it on globally hangs any
site that silently probes FedCM at load. End-to-end run against the canonical demo IdP:
bun run examples/fedcm.ts.
No localhost / LAN leak (private-network block)
Fingerprinters (iphey, pixelscan, …) don't read your process list — they can't.
They port-scan 127.0.0.1 from page JavaScript, timing which local ports answer,
and map open ports to software: VNC on :5900, an antidetect API on :3001, a dev
server on :3000. That both fingerprints you and leaks your LAN to every site you
visit. Most stealth stacks (nodriver, Camoufox, Playwright-stealth) don't stop it.
Veil does, on by default. Every HTTP-family request (fetch/XHR/EventSource/
<img>/<script>) from a page to a loopback or private (127.0.0.0/8, 10/8,
172.16/12, 192.168/16, ::1, .localhost) address is failed uniformly and
instantly — the same error whether the port is open or closed — so a scan can't tell
them apart and comes back empty. (That's the vector real detectors use; the :3001
antidetect API and :5900 VNC probes are plain HTTP.)
const browser = await Browser.launch(); // block is on
const browser = await Browser.launch({ blockPrivateNetwork: false }); // opt out
// per-page, toggle at runtime:
await page.blockPrivateNetwork();
await page.unblockPrivateNetwork();Origin allowlist — confine the agent when you attach to a signed-in profile
Browser.connect() attaches to a Chrome you already run, which is the only way to drive
a logged-in profile — and it hands the agent every session in that jar. An agent told
"check my order" can navigate to your mailbox, because it's the same browser. The
allowlist is how a run says where it may go instead of being trusted to stay on task:
const browser = await Browser.connect("127.0.0.1:9222", { allowOrigins: ["github.com"] });
// or per page, at runtime:
await page.restrictOrigins(["github.com", "api.github.com"]);
await page.unrestrictOrigins();Any document navigation — top-level or sub-frame — to a host outside the list fails
with AccessDenied. An entry matches its own host and subdomains on a dot boundary:
github.com covers api.github.com and not notgithub.com.
What it does not do, stated plainly, because a security control that is over-trusted is worse than none:
Subresources are not gated. A real page pulls images, fonts and scripts from other origins; gating those breaks every site, and a guard that breaks sites gets switched off. Cross-origin reads are already stopped by the same-origin policy — what this closes is the agent navigating somewhere and acting as the signed-in user.
Everything on an allowed origin is fully reachable, as that user. Allowlisting
github.comgrants the agent your GitHub.A beacon-style POST to an unlisted origin is not blocked (it isn't a document).
Still allowed by the private-network block: the agent's own top-level navigation to a
private host (page.goto("http://localhost:3000")), and a localhost page loading its own
localhost resources — only a public page reaching a private host is blocked. Known gaps (honest):
raw WebSocket to a private host isn't interceptable via CDP's Fetch domain, so those
fall back to Chrome's own Private Network Access (a timeout, not a uniform block); and
exotic IP encodings (decimal/hex) aren't matched — real-world scanners use the canonical
forms above.
Detection scorecard (measured, Chrome 148)
Run it yourself: bun run examples/detect.ts (headless) or VEIL_HEADFUL=1 bun run examples/detect.ts (headful — Veil auto-starts its own Xvfb, no wrapper needed).
Measured on an AMD Radeon (Renoir APU) host, real hardware GL via ANGLE/EGL:
Detector | Mode | sannysoft | CreepJS "headless" | CreepJS "stealth" |
Veil — headful + auto-Xvfb + real GPU | recommended | 57/57 | 0% | 0% |
Veil — headless + real GPU | server/fast | 57/57 | 33% | 0% |
(earlier: SwiftShader + heavy stealth) | superseded | 57/57 | 67% | 20% |
Live targets — the full scrapingcourse.com challenge
suite, reproducible with bun run examples/scrapingcourse.ts (residential IP, headful):
Target | Result |
Antibot Challenge | Bypassed — "You bypassed the Antibot challenge" (~3s auto-solve) |
Cloudflare JS Challenge | Bypassed — "You bypassed the Cloudflare challenge" |
Cloudflare Antibot + login | Bypassed — cleared the wall, rendered the real login form |
Cloudflare Turnstile + login | Passed — managed Turnstile issues its token to real Chrome (a 700+ char |
Demo suite — JS rendering, infinite scroll, pagination, table parsing, load-more, CSRF/login | all served clean |
Reddit — incl. its JS challenge | served clean (challenge auto-solved) |
Instagram — public profile | served clean |
12/12 cleared on a clean residential IP. Two honest caveats, not hidden: Cloudflare's JS interstitial difficulty scales with IP reputation — hammer one IP and it escalates (that's IP rep, not a browser tell; use proxies at volume). And what we do not yet claim: an interactive checkbox reCAPTCHA/Turnstile that demands a human click, enterprise DataDome/Kasada, and high-volume behavioural trust on logged-in sessions. We test before we claim.
What moved the needle (each verified by re-running the suite):
Real GPU, not SwiftShader.
--use-gl=angle --use-angle=gl-egldrives the actual AMD GPU → an authentic, self-consistent WebGL fingerprint. No vendor spoof = no lie for CreepJS's pixel-hash to catch.Headful on a server. Veil manages its own Xvfb display, so "headful" needs no desktop. Eliminates the headless render quirks + tiny-screen tell (33% → 0%).
Slim, self-gating stealth. The biggest surprise: the stealth patches themselves were the "20% stealth" signal. A correctly-launched Chrome already reports
webdriver === false(the right human value — forcingundefinedis worse), 5 plugins, a realchromeobject. So each patch now fires only when the value is genuinely anomalous; on healthy Chrome it's a no-op. Smaller surface = nothing to detect.
Use from an AI agent (MCP)
Veil ships an MCP server (src/mcp.ts) — already wired into persoje
(~/.config/persoje/mcp.json), exposing 50 tools, including the composite/batch
primitives built for agent-operation velocity (goto_and_wait, click_and_wait,
extract_many, fill_form, batch — collapse an 8-call flow to as few as 3, see
docs/AGENT-GUIDE.md for the full usage guide + a runnable
demo) and verify_url (ground-truth check outside the browser session, no
cookies/login). Tool-execution failures come back as isError results (the
model reads and self-corrects) rather than JSON-RPC errors. Verified
end-to-end through persoje's own MCP client (discover → goto → snapshot). Any
MCP host works.
Driving a heavy/virtualized SPA (Ancestry, Notion, Figma-style editors)
veil_snapshot walks the accessibility tree and can stall or time out on a big virtualized
page. Don't hand-roll a workaround per site — three tools already solve the pieces:
Find and click without a snapshot ref:
veil_click_text(orveil_domfirst if you need to see what's there) — one in-page pass that pierces shadow DOM, scrolls the match into view, and does a TRUSTED click at freshly-read coordinates. This is what replaced the original ad-hocevaluate(getBoundingClientRect) → click_atdance.Wait for the page to catch up:
veil_wait_for(poll a JS expression) orveil_wait_for_selector(poll a CSS selector, optionallyvisible:true) — a patient wait instead of a fixed sleep.Capture a download it triggers:
veil_enable_downloadsonce, then click, thenveil_wait_for_download— Chrome under CDP silently cancels downloads otherwise. Driving from a script instead of MCP?Page.downloadAfter(trigger, {dir})composes all three calls in the order that avoids the finish-before-you-await race.
The package ships a veil-mcp bin, so an installed user can launch the server without a
checkout — copy-pasteable into any MCP host:
{ "servers": { "veil": {
"command": "npx",
"args": ["-y", "-p", "@achamm/veilbrowser", "veil-mcp"],
"env": {} // headful + auto-Xvfb + real GPU (0% CreepJS).
// Set VEIL_HEADLESS=1 for the faster server mode.
} } }Smoke-check the bin (returns the tools list, no browser launched):
echo '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | npx -y -p @achamm/veilbrowser veil-mcpLocal dev alternative (from a checkout, no build step):
{ "servers": { "veil": {
"command": "bun",
"args": ["run", "src/mcp.ts"] // run from the repo root
} } }Point it at a browser you already have open
Set VEIL_CDP_URL and the server drives an existing Chrome instead of launching its own —
the MCP counterpart of Browser.connect(), and the only way an agent gets at sessions a
human signed into by hand:
{ "servers": { "veil": {
"command": "npx",
"args": ["-y", "-p", "@achamm/veilbrowser", "veil-mcp"],
"env": { "VEIL_CDP_URL": "127.0.0.1:9333" }
} } }google-chrome --user-data-dir=/path/to/profile --remote-debugging-port=9333 about:blank &It takes the tab that is already open rather than adding a blank one, and if that Chrome is
unreachable it falls back to launching — an absent browser downgrades the server, it does not
kill it. Read docs/SECURITY.md before attaching an agent to a profile
that holds your real sessions: the agent can drive every logged-in session in that profile, and veil_eval can read any cookie the page can.
VEIL_ALLOW_ORIGINS limits where it can navigate; popups, subresources and veil_eval are not covered
(docs/SECURITY.md).
Server env for attaching safely:
Variable | Effect |
| Attach to this Chrome ( |
| If the attach fails, return an error naming the fix instead of launching a second Chrome on the same profile. |
| Comma-separated navigation allowlist ( |
|
|
| Per-call deadline (default 45 s, longer for wait/batch tools). A call's own |
Cookie redaction covers veil_get_cookies only. veil_eval("document.cookie") still returns
every cookie that is not HttpOnly, and any page script the agent runs can read them. Redaction keeps
values out of casual tool output; it does not stop an agent that sets out to read them.
Two failure modes this removes, both of which surface as a bare CDP connection closed that
reads like a network fault:
A Chrome already holds the
user-data-dir. Chrome refuses a second instance on a locked profile, so the launch path could never work on exactly the profile worth driving.The browser quits while the server lives on. A cached connection to a dead Chrome fails every later call until the server is restarted. It now notices and reconnects.
bun run examples/mcp-attach-check.ts 127.0.0.1:9333 --recovery # checks both, end to endTesting
bun run examples/selftest.ts # end-to-end: launch, stealth, snapshot, interact
bun run examples/detect.ts # bot-detection scorecard (bot.sannysoft.com, etc.)
bun test # unit tests (browser-launching ones skip under CI)
DISPLAY=:98 python3 python/tests/test_smoke.py # 21 checks, Python front end vs real ChromeUnit tests cover:
PRNG (
human.test.ts): xorshift32 determinism, range/int bounds, keystroke cadence, mouse timingSnapshot refs (
snapshot.test.ts): ref numbering (1-based, sequential on a fresh document), AX-tree filteringOrigin allowlist (
origin-allowlist.test.ts): host+subdomain matching on a dot boundary (notgithub.comrejected), navigation to an unlisted host blocked, subresources deliberately not gated, unrestricted when unsetRef identity across snapshots (
ref-cross-snapshot.test.ts): a survivor keeps its ref when an element above it is removed or inserted; a removed element's ref fails loudly; a stale ref never actuates a different element; numbering resets on navigationCDP framing (
cdp-messages.test.ts): JSON-RPC structure, sessionId routing, command/response correlationPrivate-network classifier (
private-host.test.ts): loopback/RFC1918 vs public host detection (the block's decision)Lifecycle (
lifecycle.test.ts, local only): launch/close, process-group reaping, profile-lock refusalPython parity (
python-parity.test.ts): the Python front end's assembled stealth script is byte-identical to this one for every preset, the committed generated assets match what the generator emits now, and the injected scripts are pure ASCII (bun's transpiler corrupts non-ASCII insideString.raw)
Status
Working today (verified against Chrome 148):
Zero-dep CDP runtime (raw WebSocket, flat session mode)
Stealth launch + page-script injection (
--disable-blink-features=AutomationControlled)UA/client-hint scrub (no "HeadlessChrome" token)
WebGL backend selection (hardware GPU via ANGLE/EGL, or SwiftShader + vendor masking)
AX-tree snapshot → stable integer refs for agent-friendly interaction
Human-like input: curved Bézier mouse paths, jittered keystroke timing, real CDP input
PNG screenshots (vision-model ready)
Headful-on-server via auto-managed Xvfb — "headful" with no desktop (best fingerprint scores)
FedCM sign-in — drives the native "Sign in with Google" /
credentials.get()account chooser over CDP (examples/fedcm.ts)No localhost/LAN leak — blocks visited sites from port-scanning your private network (on by default)
Clean process lifecycle — detached process groups + a reaper, so Ctrl-C/crash never orphans Chrome
MCP server (
src/mcp.ts) — stdio JSON-RPC; persoje, Claude, any MCP host drives Veil natively
Roadmap toward production:
Adversarial fingerprint suite — continuous scoring (CreepJS, sannysoft, Datadome demo)
Runtime.enable-leak hardening via isolated worlds for all evalProfile + residential-proxy pools (the "Veil Cloud" layer)
Vision-based element grounding fallback (sparse AX-trees, canvas apps)
Response-body capture; session persistence & profile warm-up
Per-tab concurrency (many tabs, one socket — transport already supports it)
Who builds this
Veil is built and maintained by HamTek.
We build it because we need it. Our own agents drive real browsers all day — posting, scraping, filling in forms on sites that actively look for automation. The standard tools announce themselves (see the table above), so we wrote the layer that doesn't. Veil is what we run in production, every day.
That's also the work we do for other people: agents that hold up once real users get to them, not just in the demo. If that's the problem you have, we're at hamtek.dev.
License
MIT.
Available Tools
33 toolsveil_attributeA
Read one attribute of an element by snapshot ref (e.g. href, value, aria-label, a data-* attribute). Returns the raw string, or null if absent.
Inputs: ref (required), name (required).
veil_backA
Go back one entry in session history (errors if there's nothing earlier). waitUntil 'load' (default) or 'networkidle'.
Inputs: waitUntil.
veil_block_resourcesA
Block resource loads to speed up scraping and shrink your footprint — by type (image, font, media, stylesheet, script, xhr, fetch, document, websocket, ...) and/or by URL substring. Calls accumulate; coexists with the private-network guard. Lift with veil_unblock_resources.
Inputs: urls, types.
veil_clickB
Click an element by its snapshot ref (human-like mouse path).
Inputs: ref (required).
veil_click_atA
Trusted click at absolute viewport coordinates (x, y). Use when there is no snapshot ref to target — a canvas, map, or custom widget.
Inputs: x (required), y (required).
veil_closeA
Close the browser.
Inputs: no named parameters.
veil_dragA
Drag from one point to another — real mousedown -> mousemove(button held) -> mouseup, not the HTML5 drag events. Use this for 'drag a card onto a canvas' UIs (site/page builders, Kanban boards, sortable lists) whose drop targets don't respond to a plain click. Pass ref for the source if it has a snapshot ref, otherwise fromX/fromY; the destination is almost always a plain div with no ref, so give toX/toY read off a veil_screenshot.
Inputs: toX (required), toY (required), ref, fromX, +1 more.
veil_evalB
Evaluate a JS expression in the page and return the value.
Inputs: expression (required).
veil_fedcm_enableA
Arm FedCM interception BEFORE navigating to a site that shows a Google/federated 'one-tap' sign-in on load. Order: veil_fedcm_enable -> veil_goto the sign-in page -> veil_fedcm_signin. (Skip this for an active 'Sign in with Google' button; veil_fedcm_signin arms itself when you pass a triggerRef.)
Inputs: no named parameters.
veil_fedcm_signinA
Complete a federated ('Sign in with Google', FedCM) login that Chrome renders as a native chooser no click can reach: waits for the intercepted account chooser, selects an account, and returns it. Pass triggerRef to first click an active sign-in button; omit it for one-tap/passive flows (call veil_fedcm_enable before navigating). accountIndex defaults to 0.
Inputs: triggerRef, accountIndex.
veil_fillC
Click a field by ref and type text into it (human cadence).
Inputs: ref (required), text (required).
veil_forwardA
Go forward one entry in session history (errors if there's nothing later). waitUntil 'load' (default) or 'networkidle'.
Inputs: waitUntil.
veil_framesA
List cross-origin child iframes discovered on the current page (e.g. a drag-and-drop site builder whose whole canvas is one iframe on a different subdomain). Same-origin iframes don't need this — they already show up in a normal veil_snapshot. Call after veil_goto if a page you expect to interact with returns '(no interactive elements)'.
Inputs: no named parameters.
veil_get_cookiesA
Return the browser's current cookies as JSON (name, value, domain, path, expires, httpOnly, secure, sameSite, ...). Symmetric with cookie injection. Optionally pass urls to scope the read to specific origins.
Inputs: urls.
veil_gotoA
Navigate the browser to a URL (launches Chrome on first call). waitUntil 'load' (default) or 'networkidle' (wait until no network for ~500ms — better for SPAs that fetch after load).
Inputs: url (required), waitUntil.
veil_pdfA
Render the current page to a PDF and save it to disk — Chrome prints PDF in HEADLESS mode only (VEIL_HEADLESS=1). Pass path for the output file, or omit to write a temp file; returns the saved path. Options: landscape, printBackground (default true), scale, pageRanges.
Inputs: path, scale, landscape, pageRanges, +1 more.
veil_pressA
Press a single named key on the focused element. Use 'Enter' to submit a search box or form (fill a field, then veil_press Enter). Supported: Enter, Tab, Escape, Backspace, Delete, ArrowUp, ArrowDown, ArrowLeft, ArrowRight, Home, End, PageUp, PageDown.
Inputs: key (required).
veil_reloadA
Reload the current page. waitUntil 'load' (default) or 'networkidle'.
Inputs: waitUntil.
veil_screenshotA
Capture a PNG screenshot (returned as an image for vision). Default is the current viewport. Pass a snapshot ref to shoot just that element's bounding box, clip for an explicit {x,y,width,height} page rectangle, or fullPage:true for the whole scrollable page.
Inputs: ref, clip, fullPage.
veil_scrollA
Scroll the page by a pixel delta via a real mouse-wheel event (positive dy scrolls down, positive dx scrolls right). Reveals lazy-loaded / off-screen content; re-run veil_snapshot after.
Inputs: dy (required), dx.
veil_selectA
Set a dropdown (by snapshot ref) to a value and fire input+change — the reliable way to drive a native , which click+type can't. Value matches an option's value, then its visible label/text.
Inputs: ref (required), value (required).
veil_set_fingerprintA
Apply a COHERENT fingerprint/profile — UA + client hints + navigator.platform, screen, timezone/locale/geolocation, WebGL vendor/renderer, and seeded canvas/audio noise, all internally consistent. Pass a preset name, random:true (+ optional seed for a deterministic identity), or a full fingerprint object. Call this BEFORE veil_goto for full effect: the injected values take hold on the next navigation; the UA/client-hint/timezone/screen overrides apply immediately. This is coherent identity control, not a magic bullet.
Inputs: seed, preset, random, fingerprint.
veil_set_user_agentA
Override the User-Agent at runtime, keeping the Sec-CH-UA client-hint brands aligned with it (a bare UA with mismatched hints is a fingerprint tell).
Inputs: userAgent (required).
veil_set_viewportA
Set the viewport size (and optional deviceScaleFactor / mobile emulation) — the page sees this as window.innerWidth/Height, screen size, and devicePixelRatio. Emulate a phone or force a fixed desktop size for reproducible screenshots.
Inputs: width (required), height (required), mobile, deviceScaleFactor.
veil_snapshotA
Return the page as a numbered list of interactive elements from the accessibility tree. Use the [ref] numbers with veil_click / veil_fill. No CSS selectors needed.
Inputs: no named parameters.
veil_textB
Read one element's rendered text (innerText) by snapshot ref — a price, status, or result cell — without dumping the whole page.
Inputs: ref (required).
veil_typeC
Type text into the currently focused element.
Inputs: text (required).
veil_unblock_resourcesA
Lift all resource blocking set by veil_block_resources (leaves the private-network guard untouched).
Inputs: no named parameters.
veil_uploadA
Attach local files to a file (even a hidden one) without an OS file picker. Paths must be absolute. selector defaults to the first input[type=file]; pass a specific one if the page has several.
Inputs: paths (required), selector.
veil_upload_via_pickerA
Attach files through a control that opens a file picker (SPAs like Gemini that create the lazily on click). Pass the snapshot ref of the trigger element and absolute file paths.
Inputs: paths (required), triggerRef (required), timeout.
veil_use_frameA
Point every following veil_snapshot/veil_click/veil_fill/veil_type/veil_eval call at one child iframe (index from veil_frames), instead of the main page. Omit index (or pass null) to switch back to the main page. Existing refs are invalidated on switch — call veil_snapshot again after switching.
Inputs: index.
veil_wait_forA
Poll a JS expression in the page until it is truthy, instead of a fixed sleep — e.g. "document.querySelector('.results')". Returns when the condition holds; errors on timeout.
Inputs: expression (required), poll, timeout.
veil_wait_for_selectorA
Poll until a CSS selector matches, then return (the selector-shaped convenience over veil_wait_for). Pass visible:true to also require the element to be laid out and not display:none/visibility:hidden. Errors on timeout.
Inputs: selector (required), timeout, visible.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
Loading tool schema changelog…
TDQS
Scored across 33 tools
Each tool targets a specific browser automation action with minimal overlap. For example, 'veil_fill' is for clicking a field and typing, while 'veil_type' is for typing into the focused element, and descriptions clearly distinguish them.
All tools follow a consistent 'veil_' prefix with a verb or verb_noun pattern, such as 'veil_goto', 'veil_set_viewport', 'veil_wait_for_selector', making the naming predictable and intuitive.
With 33 tools, the server covers a broad range of browser automation needs (navigation, interaction, extraction, resource control, etc.), which is appropriate for its comprehensive scope, though slightly on the higher side.
The tool set covers most essential browser automation operations, including navigation, interaction, data extraction, resource blocking, fingerprinting, and screenshots. Missing features like dialog handling are minor and do not hinder typical workflows.
Maintenance
Related MCP Connectors
Stealth web automation for AI agents. Login, signup, navigate, screenshot.
Stealth web automation for AI agents. Login, signup, navigate, screenshot.
Give AI agents a real cloud Chrome: open sessions, navigate, read pages, click, type and screenshot.
Control a real browser from AI agents: navigate, click, type, screenshot, read the page.
Related MCP Servers
- AlicenseAqualityCmaintenanceEnables AI clients to control the user's already-open, logged-in browser pages in real time over a local WebSocket channel, without Playwright, Puppeteer, Selenium, or any browser driver. Exposes tools for navigation, semantic page snapshots, clicking, form filling, JavaScript evaluation, screenshots, network monitoring, cookie handling, and tab management via the CDP.20MIT
- AlicenseBqualityBmaintenanceEnables AI agents to drive the user's already-running Google Chrome through a WebSocket bridge, listing and switching tabs, navigating, clicking, typing, scrolling, extracting DOM, taking screenshots, and evaluating JavaScript. It works without restarting Chrome and preserves all existing logins, cookies, and 2FA sessions.253 npmMIT
- AlicenseBqualityBmaintenanceEnables AI agents and developers to automate real Chrome/Chromium browsers through the Chrome DevTools Protocol, with token-efficient snapshots, multi-action batching, shadow DOM traversal, system-page control, extension management, and network/WebSocket inspection.811MIT
- AlicenseNot gradedqualityCmaintenanceEnables AI agents to drive a real headless Chrome over the DevTools Protocol without any extension, exposing tools to list, open, navigate and read tabs as compact accessible outlines with element refs, click, type, scroll, take screenshots, and inject scripts. It also runs horizontal-overflow and WCAG AA contrast audits via both an MCP tool and a CI-friendly CLI.10 npmMIT