byob

Bring Your Own Browser — let your AI assistant use the Chrome you already have open.

English · 中文

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byob is a local MCP server that lets AI coding tools (Claude Code, Cursor, Cline, Windsurf, etc.) directly control your real Chrome — the one where you're already logged into everything.

"read my Twitter timeline and summarize the top 5 posts"
"google 'mcp protocol spec', click the first result, read the page"
"take a screenshot of example.com"
"grab my GitHub session cookie so I can curl with it"
"open my Gmail tab and tell me how many unread"

	WebFetch	Headless Puppeteer	byob
Sees logged-in pages	❌	⚠️ manual cookie copy	✅ already logged in
Passes bot detection	❌	❌	✅ real human browser
Setup time	0	hours	~5 min
Cloud cost	free	$$	free

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Install

Quick install (recommended)

curl -fsSL https://raw.githubusercontent.com/wxtsky/byob/main/install.sh | bash

The script checks prerequisites (Node.js ≥ 20, bun, Chrome), clones the repo, builds everything, and walks you through MCP registration interactively. If bun is not installed, it offers to install it for you.

Set BYOB_INSTALL_DIR to change the install location (default: ~/byob).

Manual install

Prefer to do it yourself?

Requires Node.js ≥ 20, bun, Chrome, and any MCP-compatible AI tool.

git clone https://github.com/wxtsky/byob
cd byob
bun install
bun run setup

bun run setup walks through the install interactively:

1. Pick output language (English / 中文)
2. Generates a unique extension key for you
3. Builds the Chrome extension
4. Writes the config that lets Chrome talk to byob
5. Prompts you to multi-select your AI tools, then registers each one (CLI tools via their mcp add command, JSON-config tools by writing the config file directly)

After the script finishes, three manual steps remain:

Step 2 — Load extension in Chrome

Open chrome://extensions in Chrome.

1. Top-right → turn ON Developer mode
2. Top-left → click Load unpacked
3. Select the folder printed in your terminal, something like:

   /your/path/to/byob/packages/extension/output/chrome-mv3
   

Step 3 — Restart Chrome

Quit Chrome completely (⌘Q on Mac / close all windows on Windows), then reopen.

Closing a single tab or window is not sufficient — Chrome only reads the Native Messaging config at startup.

Step 4 — (Reference) Manual MCP registration

The setup script registers your selected tools automatically. The block below is for reference only — use it if you skipped the prompt or want to register a different tool later:

Claude Code

claude mcp add byob -s user -- /path/to/tsx /path/to/byob-mcp.ts

To enable browser_eval, add -e BYOB_ALLOW_EVAL=1 after -s user.

Codex CLI

codex mcp add byob -- /path/to/tsx /path/to/byob-mcp.ts

Cursor

Add to .cursor/mcp.json (project) or ~/.cursor/mcp.json (global):

{
  "mcpServers": {
    "byob": {
      "command": "/path/to/tsx",
      "args": ["/path/to/byob-mcp.ts"]
    }
  }
}

Windsurf

Add to ~/.codeium/windsurf/mcp_config.json (same JSON format as Cursor):

{
  "mcpServers": {
    "byob": {
      "command": "/path/to/tsx",
      "args": ["/path/to/byob-mcp.ts"]
    }
  }
}

Cline (VS Code)

Open Cline sidebar → MCP Servers → Configure, then add (same JSON format):

{
  "mcpServers": {
    "byob": {
      "command": "/path/to/tsx",
      "args": ["/path/to/byob-mcp.ts"]
    }
  }
}

The actual paths are printed by the setup script. The examples above use shortened paths for readability.
To enable browser_eval, add "env": { "BYOB_ALLOW_EVAL": "1" } to the config (or -e BYOB_ALLOW_EVAL=1 for CLI tools).

Step 5 — Wait for setup to confirm the bridge is online

After you finish steps 2 and 3 (load the extension and ⌘Q-restart Chrome), setup auto-detects the bridge coming online and prints ✓ bridge online. The installation is complete — open a new session in your AI tool and try "use byob to read ...".

If you exited setup early with Ctrl+C, or want to check the state later:

bun run doctor

bun run doctor prints actionable fixes under every ✗ (e.g. "⌘Q-restart Chrome", "extension ID mismatch", etc.).

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Tools

Tool	What it does
browser_read	Open a page, scroll through, read all text
browser_read_markdown	Same, returns clean markdown (no nav/ads)
browser_extract_table	Pull <table> elements as JSON
browser_get_console_logs	Snapshot console.log / warn / error
browser_start_record_network	Start recording HTTP + WebSocket traffic
browser_stop_record_network	Stop recording, export JSON or HAR
browser_screenshot	Screenshot → saved to disk
browser_download_images	Download all images from a page
browser_click	Click a button or link
browser_type	Type into an input (optionally press Enter)
browser_press_key	Send a keyboard key (Enter, Escape, F5, ArrowDown, ...)
browser_hover	Hover the mouse over an element to trigger tooltips/menus
browser_select	Choose an option in a native <select>
browser_scroll	Scroll to top/bottom, an element, or a Y coordinate
browser_get_html	Get raw HTML of an element or the whole page
browser_get_cookies	Export cookies for curl / scripts
browser_navigate	Open a URL in a new or existing tab
browser_go_back	Go back one step in browser history
browser_go_forward	Go forward one step in browser history
browser_wait_for	Wait for an element to appear
browser_list_tabs	List all open tabs
browser_switch_tab	Switch to a tab
browser_close_tab	Close a tab by tabId
browser_eval	Run JavaScript on the page (off by default)
browser_set_cookies	Write a cookie via chrome.cookies.set (CHIPS-aware).
browser_print_pdf	Save current page as PDF (default ~/.byob/pdfs/).
browser_get_storage	Read localStorage / sessionStorage for an origin.
browser_get_performance	Page Web Vitals + navigation timing.
browser_upload_file	Upload local files to <input type="file">.
browser_intercept_start	Start a stateful request-interception session.
browser_intercept_stop	Stop a browser_intercept_start session and return hit stats.
browser_drag	Drag the mouse from one point to another (linear interpolation).
browser_emulate_device	Emulate mobile/tablet viewport / DPR / touch / UA.

17 of these tools support framePath to reach into nested iframes (including cross-origin).

Full schemas: shared/src/schemas.ts

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How it works

AI tool → byob-mcp → byob-bridge → Chrome extension → your tab
         (stdio)    (Unix socket) (Native Messaging) (Chrome DevTools Protocol)

All communication stays local. No data leaves your machine. When Chrome closes, all byob processes exit automatically.

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Everyday commands

bun run setup      # install or re-install
bun run doctor     # check what's working
bun run bridges    # list running bridge processes
bun run logs       # tail the bridge log
bun run unsetup    # remove everything

All run from the byob repo root.

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Reliability

• End-to-end cancellation. Ctrl+C propagates through the entire chain (MCP → bridge → extension → Chrome), cleanly detaching all debug sessions.
• DevTools conflict handling. If DevTools is open on a tab, browser_eval automatically falls back to chrome.scripting.executeScript.
• Sleep/wake recovery. After a laptop sleep cycle, byob resets all debug sessions so the next call starts from a clean state.

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Security

• browser_eval is off by default — enable with BYOB_ALLOW_EVAL=1. Every call logs + notifies.
• chrome://, file://, Google/MS/Apple login pages are blocked by default.
• Each install gets a unique extension key — no collisions.
• Socket files are 0600, dirs are 0700. Other users can't see them.
• Zero outbound network traffic. No analytics, no pings, no crash reports.
• Chrome displays a "byob is debugging this browser" banner on active tabs. This is a Chrome security feature and cannot be suppressed.

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Troubleshooting

Symptom	Cause	Fix
No live bridge	Chrome not running or extension disabled	Check chrome://extensions
cdp_attach_failed	DevTools open on that tab	Close DevTools
url_forbidden	URL on the blocklist	See Security section
extension_not_connected	Extension lost connection	Reload at chrome://extensions
Nothing works after install	Chrome was not fully restarted	Quit Chrome completely (⌘Q) and reopen

Run bun run doctor for detailed diagnostics on which step failed.

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Platform notes

Platform	Auto	Manual
macOS	Auto-registers selected MCP tools	Open chrome://extensions and load the unpacked extension
Windows	Same + writes Native Messaging host to registry	Same as macOS
Linux	Auto-registers selected MCP tools	Same as macOS

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More

• Changelog
• Contributing
• Design notes
• Test checklist

MIT licensed. byob has broad access to your browser — only use it on machines and accounts you own.