Reasonix Browser Bridge

Reasonix 的自动化浏览器插件（开源）—— 通过 MCP 让 Reasonix 直接控制你的浏览器：标签页、Cookie、任意 JavaScript 执行。Chrome / Edge 通用。

┌─────────────┐   stdio / MCP   ┌──────────────────┐   WebSocket    ┌───────────────┐
│  MCP Client │ ⇄─────────────⇄ │  MCP Server (Node)│ ⇄ 127.0.0.1:8747 ⇄ │  Extension    │
│ (Reasonix…) │                 └──────────────────┘                 │ (MV3)         │
└─────────────┘                                                      └───────┬───────┘
                                                                            │
                                                                   tabs / cookies /
                                                          scripting / debugger (CDP)
                                                                            ▼
                                                                        Browser

• Extension (extension/): Manifest V3, connects to ws://127.0.0.1:8747, auto-reconnects. Install once per browser (Chrome and Edge).

• MCP Server (server/): stdio MCP server that bridges to the extension and exposes browser tools.

• No special flags needed to launch the browser — no --remote-debugging-port, no native host / registry setup. Install the extension, run the server, done.

Features / Tools

Auto-update check: the extension checks GitHub Releases every 12h (and on browser start). When a new version is published you'll get a system notification, an orange ↑ badge on the toolbar icon, and a "Download" button in the popup — no store required (works for Developer-mode installs).

Multi-browser: Chrome and Edge are both supported. Install the extension in each browser you want to control — every instance auto-connects to the bridge. Most tools accept an optional browser parameter ("chrome" / "edge") to target a specific browser; when only one browser is connected it is used automatically, and when several are connected without a browser argument the server tells you to specify one.

Related MCP server: Chrome MCP Server

Install

1. Install the extension (Chrome / Edge — install once per browser)

1. Open chrome://extensions (Chrome) or edge://extensions (Edge).

2. Enable Developer mode.

3. Click Load unpacked / 加载未打包的扩展程序 and select the extension/ folder.

4. Pin it if you like — the icon shows bridge status (green M = connected).

Note: Chrome 137+ blocks the --load-extension command-line flag on branded builds; the developer-mode UI install above is the supported way. The same extension folder works in both browsers (same extension ID).

2. Start the MCP server

cd server
npm install
npm start

You should see ✅ 插件已连接 / plugin connected once the extension auto-connects.

3. Configure your MCP client

Add to your MCP client config (Reasonix config.toml):

{
  "mcpServers": {
    "reasonix-browser-bridge": {
      "command": "node",
      "args": ["/absolute/path/to/server/index.js"]
    }
  }
}

Usage example

Ask your AI:

List my open tabs. Then run document.title on tab #123.

It maps to browser_tabs_list and browser_script_execute.

browser_script_execute takes a JS expression (no return keyword; use an IIFE for async):

document.title
({ count: document.querySelectorAll('a').length })
(async () => { const r = await fetch('/api/data').then(r => r.json()); return r; })()   // set awaitPromise: true

Security

• The WebSocket bridge binds to 127.0.0.1 only; the extension only connects to localhost.

• No remote access, no native messaging, no registry changes.

• The extension requests full permissions (tabs, cookies, scripting, debugger, downloads, proxy, browsingData, management, history, bookmarks, clipboard, notifications, ... + <all_urls>) — it is designed as Reasonix's automation bridge, so it can do anything the browser can. Install it only if you trust this project.

Project layout

browser-mcp-bridge/
├── extension/      # MV3 browser extension
│   ├── manifest.json
│   ├── background.js   # WS bridge + browser gateway
│   ├── popup.*         # minimal status popup
│   ├── content.js      # page marker (document_start)
│   └── icons/
├── server/         # MCP server (Node)
│   ├── index.js
│   └── package.json
├── README.md
└── LICENSE

License

MIT