Koko browser profiles bundle fingerprint signals — user agent, Client Hints, canvas/audio/WebGL probes, fonts, voices, and cookie seeds — so automation sessions present consistent identity across runs.

Profile location

browser/profiles/
  chrome-macos-catalina.json
  chrome-macos-sonoma.json
  chrome-windows-11.json
  chrome-local-huys-macbook-pro.json
  assets/          # per-profile probe baselines
  sessions/        # persisted cookie jars

Profile structure

Each profile JSON includes:

navigator — userAgent, platform, hardwareConcurrency, languages
userAgentData — Sec-CH-UA brands and platform metadata
screen — viewport and color depth
webgl, canvas, audio — probe references into assets/
policies — e.g. google-search transport rules

Launch with profile

# CDP server
zig-out/bin/koko serve \
  --browser-profile chrome-macos-catalina \
  --host 127.0.0.1 --port 9222

# SDK
const launched = await Browser.launch({
  profile: "chrome-macos-catalina",
  cookieJar: "browser/profiles/sessions/my-session-cookies.json",
});

Cookie persistence

Use --cookie-jar to read/write session cookies across runs. Pair with captureSessionState() / restoreSessionState() for storage snapshots.

Fingerprint probes

Probe	Command
CreepJS vs Chrome	`npm run test:creepjs:compare`
CreepJS local sections	`npm run test:creepjs:local`
BrowserLeaks	`npm run test:browserleaks`
Profile CDP smoke	`npm run test:profile -- --profile chrome-macos-catalina`

Google Search policy

Profiles with google-search policy use real Chrome network transport via scripts/chrome-google-transport.mjs. See repo docs/tls-impersonate.md and google-search-debug/.