Browser MCP

TypeScript MCP server + Chrome extension — automate your real browser with AI (Cursor, Claude, VS Code, Windsurf, …).

Inspired by BrowserMCP/mcp: same architecture (stdio MCP ↔ WebSocket ↔ extension), expanded toolset (vision/SOM, code execution, macros, watchdogs).

┌──────────────────┐   MCP stdio    ┌─────────────────────────┐
│  AI client       │ ─────────────► │  @browser-mcp/mcp       │
│  Cursor / Claude │ ◄───────────── │  (Node.js / TypeScript) │
└──────────────────┘                └───────────┬─────────────┘
                                                │ WebSocket :17373
                                                ▼
                                    ┌─────────────────────────┐
                                    │  Chrome extension (MV3) │
                                    │  your real profile      │
                                    └─────────────────────────┘

No Python. No remote browser farm. Everything runs locally on your machine.

Why this exists

Related MCP server: byob

Features

• Vision (Set-of-Mark) — screenshot with numbered interactive elements

• Human-like input — Bezier mouse paths, typed key delays

• Code execution — run JS in the page or Node/Playwright on the host

• Tabs, cookies, storage, network intercept

• Extract data / PDF

• Macros — record & replay flows

• Watchdogs — background condition polling

Repo layout

packages/
  shared/      # WS protocol types (shared by MCP + extension)
  mcp/         # TypeScript MCP server (stdio + WS hub)
  extension/   # Chrome MV3 extension (load unpacked from dist/)

Quick start

1. Install & build

git clone git@github.com:pomoq-dev/browser-mcp.git
cd browser-mcp
npm install
npm run build

2. Load the Chrome extension

1. Open chrome://extensions

2. Enable Developer mode

3. Load unpacked → select packages/extension/dist

4. Pin the extension

3. Point your AI client at the MCP server

Cursor (~/.cursor/mcp.json) / Claude Desktop / Windsurf:

{
  "mcpServers": {
    "browser-mcp": {
      "command": "node",
      "args": ["/ABSOLUTE/PATH/TO/browser-mcp/packages/mcp/dist/index.js"]
    }
  }
}

See mcp-config.example.json.

4. Connect the tab

1. Open the page you want to automate

2. Click the extension icon → Connect (default 127.0.0.1:17373)

3. Badge turns green ON

The MCP server starts a WebSocket hub on port 17373 and speaks MCP over stdio to the AI client.

Development

npm run build          # shared → mcp → extension
npm start              # run MCP server
npm run dev            # mcp with tsx watch
npm test
npm run typecheck
npm run inspector      # MCP inspector UI
npm run build:extension

Extension watch:

npm run watch -w @browser-mcp/extension

Then reload the extension in Chrome.

Tools (overview)

Navigation & tabs: browser_navigate, browser_get_tabs, browser_new_tab, …

Vision: browser_get_visual_state, browser_get_dom_tree, browser_screenshot

Input: browser_click, browser_type_text, browser_drag_and_drop, browser_hover, …

Code: browser_exec_js_page, browser_run_node_playwright, browser_run_node_script

Session: browser_manage_cookies, browser_manage_storage, browser_intercept_network

Data: browser_extract_data, browser_generate_pdf

Macros & watchdogs: browser_record_macro_*, browser_register_watchdog, …

Full list is exposed via MCP tools/list.

Optional: CDP for Playwright tools

browser_run_node_playwright can attach via Chrome DevTools Protocol:

/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome \
  --remote-debugging-port=9222 \
  --user-data-dir=/tmp/chrome-mcp-profile

Extension mode already uses your normal profile; CDP is only for heavy host scripts.

Security

The agent gets full control of the connected browser profile (clicks, cookies, arbitrary page JS). Run only with trusted local agents.

Credits

Architecture adapted from BrowserMCP/mcp / Playwright MCP ideas: control the user's browser instead of spawning a disposable one.

License

MIT