Cookie Sync

Cookie Sync Reference

Table of Contents

• Architecture

• Environment Variables

• How It Works

• Browserbase Context Integration

• Browser Compatibility

• Security Considerations

Architecture

Cookie sync is a Node.js script that uses:

• Stagehand (@browserbasehq/stagehand) for CDP connections to both local Chrome and the cloud browser, including cookie get/set operations

• Browserbase SDK (@browserbasehq/sdk) for API calls (context creation)

Local Chrome (Stagehand) → cookie-sync.mjs → Stagehand (Browserbase) → Cloud Browser
        ↓                                          ↓                        ↓
  context.cookies()              init() creates session           context.addCookies()

Environment Variables

How It Works

Step 1: Connect to Local Chrome

The script finds Chrome's DevTools WebSocket URL in one of two ways:

• If CDP_URL is set, it resolves the browser WebSocket endpoint from that debugging endpoint (or uses the full browser WebSocket URL directly)

• Otherwise, it reads the DevToolsActivePort file created by browsers that expose remote debugging through their normal profile

Step 2: Export Cookies

Calls context.cookies() via Stagehand's Understudy layer (which uses Storage.getCookies over CDP). This returns all cookies from all domains stored in the browser — not just the active tab.

Step 3: Create Context and Session

Creates a Browserbase Context via the SDK (persistent state container) and a Stagehand session attached to that context with persist: true. This means:

• Cookies injected during this session are saved to the context

• Future sessions using the same context ID start with those cookies

• The session uses keepAlive: true so it stays open until explicitly closed

Step 4: Inject Cookies

Calls context.addCookies() via Stagehand's Understudy layer (which uses Storage.setCookies over CDP) to inject all exported cookies into the cloud browser.

Browserbase Context Integration

Contexts persist browser state (cookies, localStorage, IndexedDB) across sessions.

First sync (creates context)

node cookie-sync.mjs
# Output includes: Context ID: ctx_abc123

Subsequent sessions (reuses context)

BROWSERBASE_CONTEXT_ID=ctx_abc123 node cookie-sync.mjs

Context lifecycle

• Contexts don't expire on Browserbase's end

• Cookies within the context expire based on the website's cookie policies

• Use one context per user/identity to avoid session conflicts

• Avoid running multiple sessions with the same context simultaneously

Browser Compatibility

Supported Browsers

Enabling Remote Debugging

Chrome 146+ (recommended):

1. Navigate to chrome://flags/#allow-remote-debugging

2. Set to "Enabled"

3. Restart Chrome

Any Chrome version (requires --user-data-dir and CDP_URL):

# macOS
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --remote-debugging-port=9222 --user-data-dir=/tmp/chrome-debug
export CDP_URL=ws://127.0.0.1:9222

# Linux
google-chrome --remote-debugging-port=9222 --user-data-dir=/tmp/chrome-debug
export CDP_URL=ws://127.0.0.1:9222

# Windows
chrome.exe --remote-debugging-port=9222 --user-data-dir=%TEMP%\chrome-debug
set CDP_URL=ws://127.0.0.1:9222

Note: --user-data-dir is required because Chrome won't open the debugging port with an existing profile. This means the debug instance starts with a fresh profile — your real cookies are not available. The chrome://flags method (Chrome 146+) does not have this limitation.

Security Considerations

• Cookies are sensitive credentials. The script transfers your authenticated sessions to a cloud browser. Only use with your own Browserbase account.

• Cookies are transmitted over secure WebSocket (wss://) to Browserbase.

• The script does not log, store, or transmit cookies anywhere other than the target Browserbase session.

• Sessions created with keepAlive: true persist until explicitly closed — remember to close sessions when done.