Browser Bridge

npm version

MCP server that gives AI coding assistants direct access to the browser — navigate, click, fill forms, run JavaScript, take screenshots, and read page content.

MCP Client ←(stdio)→ mcp-browser-bridge ←(WebSocket :7483)→ Browser Extension ←(Chrome APIs)→ Browser

Works with any MCP-compatible client: Claude Code, Cursor, Windsurf, Cline, and others.

Quick Start

1. Install the extension

Install from the Chrome Web Store, or load manually:

1. Download or clone this repo.
2. Open chrome://extensions, enable Developer mode.
3. Click Load unpacked and select the extension/ folder.

Works in any Chromium browser: Chrome, Brave, Edge, Arc, Vivaldi, Opera.

2. Add to your MCP client

claude mcp add browser-bridge -- npx -y mcp-browser-bridge

{
  "mcpServers": {
    "browser-bridge": {
      "command": "npx",
      "args": ["-y", "mcp-browser-bridge"]
    }
  }
}

{
  "mcpServers": {
    "browser-bridge": {
      "command": "npx",
      "args": ["-y", "mcp-browser-bridge"]
    }
  }
}

{
  "mcpServers": {
    "browser-bridge": {
      "command": "npx",
      "args": ["-y", "mcp-browser-bridge"]
    }
  }
}

3. Verify

Start your MCP client. The extension popup should show a green Connected indicator. Call the browser_status tool to confirm.

Available Tools

All tools accept an optional tabId parameter. When omitted, they target the active tab.

Included Prompts

The server ships two MCP prompts that provide guided workflows to any connected client:

In Claude Code, these appear as slash commands: /browser-bridge:browse and /browser-bridge:qa-runner.

Configuration

The WebSocket port defaults to 7483. To change it:

• Server side: Set the BRIDGE_WS_PORT environment variable in your MCP config.
• Extension side: Change the port in the extension popup and click Reconnect.

Security

• WebSocket binds to 127.0.0.1 only — no network exposure.
• Connections restricted to browser extension origins.
• Single extension client at a time.

Troubleshooting

Extension shows "Disconnected" Check that the MCP server is running and the port is free:

# macOS/Linux
lsof -i :7483

# Windows
netstat -aon | findstr :7483

Tools return "No extension connected" Open the extension popup and click Reconnect.

Screenshots fail The target tab must be visible and focused. Background or minimized tabs cannot be captured.

browser_evaluate returns unexpected results Results must be JSON-serializable. Promises return {} — use synchronous expressions or await inside an IIFE and return a plain value.

Development

git clone https://github.com/adbarc92/mcp-browser-bridge.git
cd mcp-browser-bridge
npm install
npm run build
npm test                 # 53 tests via Vitest

Load the extension locally via chrome://extensions → Load unpacked → select extension/.

The repo includes a .mcp.json configured for local development.

License

MIT