FoxBridge MCP

Read and drive your real, logged-in Firefox from an AI assistant — over the Model Context Protocol (MCP).

FoxBridge is two coordinated pieces:

• An MCP server (foxbridge-mcp, this npm package) — reads your on-disk Firefox profile (cookies, history, sessions, localStorage) with zero native dependencies (Node's built-in node:sqlite), and hosts a local WebSocket bridge.

• A Firefox extension ("FoxBridge") — runs inside your real browser and executes the server's commands with genuine WebExtension APIs, so the assistant drives your actual, logged-in tabs.

Everything runs locally. The extension sends nothing anywhere on its own.

⚠️ Security: FoxBridge grants total read/drive access to your logged-in browser sessions — live cookies (incl. httpOnly session tokens), storage, history, and the ability to act as you on any site. Only run it with an assistant you trust, and understand that any data the assistant reads goes to that assistant. Keep it local; treat cookie/token output as credentials.

What it can do

Drive your real Firefox (via the extension — ff_* tools): ff_status, ff_list_tabs, ff_open_tab, ff_activate_tab, ff_close_tab, ff_navigate, ff_reload, ff_read_page, ff_click, ff_type, ff_scroll, ff_wait_for, ff_eval, ff_fetch (call site APIs as you), ff_download (save files with your auth), ff_network (see the tab's live XHR/fetch calls), ff_get_cookies (incl. httpOnly).

Related MCP server: ruyipage-mcp

Demo

Ask your MCP client (Claude, etc.) things like:

> Search Google for "playwright vs puppeteer" and summarize the top 5 results.
   → opens a tab, reads the results, returns a summary

> Open my exchange dashboard, wait for the balance to load, and read it.
   → ff_navigate + ff_wait_for + ff_read_page (as the logged-in you)

> What API calls does this page make? Then call the balances endpoint and give me the JSON.
   → ff_network to discover the endpoint, then ff_fetch it with your cookies

> Download the PDF linked as "Invoice" on this page.
   → ff_download saves it to ~/Downloads using your session

Read the on-disk profile (no browser needed): list_profiles, get_cookies, get_history, get_bookmarks, get_sessions, get_local_storage, get_cache_info, clear_disk_cache.

Optional standalone Playwright browser (playwright is an optional dependency): browser_start, navigate, read_page, eval_js, tab/interaction tools. Not required for the ff_* or on-disk tools.

Install

1. The MCP server

Via npm / npx — add to your MCP client config (e.g. Claude Desktop / Claude Code):

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

One-click (Claude Desktop): grab the .mcpb bundle from the Releases page and open it — Claude Desktop installs it in one click. (Build it yourself with npm run mcpb:pack.)

Requires Node ≥ 22.5 (for node:sqlite).

2. The Firefox extension

Install FoxBridge from Mozilla Add-ons (AMO): link added after the listing is approved.

Or load it from source for development: about:debugging → This Firefox → Load Temporary Add-on → pick extension/manifest.json.

The extension auto-connects to the server on ws://127.0.0.1:8787. Check with the ff_status tool.

Usage

Ask your assistant things like:

• "List my open Firefox tabs and read the active one."

• "Open my dashboard, wait for the balance to load, and read it."

• "Call this site's API as me and give me the JSON."

Configuration

• BRIDGE_PORT (env) — override the bridge port (default 8787). Useful to run isolated instances.

Development

npm install        # playwright is optional and NOT downloaded automatically
npm run build      # compile TypeScript -> dist/
npm start          # run the server on stdio

Extension packaging/signing:

npm run ext:build           # build an unsigned .xpi into dist-ext/
npm run ext:submit          # submit to AMO (listed) — needs AMO API creds

License

MIT © Sina Mohsenifar