Antigravity Chrome Bridge

License C++17 MCP Platform

Native C++ MCP server for Chrome automation — zero dependencies, instant startup, 22 tools.

The only browser automation MCP server written in native C++. Single binary, no Node.js, no Python, no runtime dependencies. Works with any MCP client (Claude Desktop, Cursor, Antigravity, etc.)

┌─────────────────────────────────────────────────────────────┐
│  antigravity-chrome-bridge.exe (~1.4MB)                     │
│                                                             │
│  ┌──── MCP Server (stdio JSON-RPC 2.0) ──── PRIMARY ────┐  │
│  │  22 tools · 3 resources · auto-detection              │  │
│  └───────────────────┬───────────────────┬───────────────┘  │
│                      │                   │                  │
│  ┌─── CDP Client ────┘  ┌── Ext Bridge ──┘                 │
│  │ WebSocket → :9222    │ HTTP → :13371                     │
│  └──────────────────┘   └──────────────────┘                │
│                                                             │
│  Language: C++17 · Libs: nlohmann/json (header-only)        │
│  Build: CMake 3.20+ · Cross-platform                       │
└─────────────────────────────────────────────────────────────┘

---

Why This Project?

Every existing Chrome MCP server is written in TypeScript or Python. This one is different:

	TypeScript MCP servers	Antigravity Chrome Bridge
Startup	~800ms	~5ms
Memory	~40–80MB	~5MB
Tool call overhead	~15ms	<1ms
Binary size	~50MB (node_modules)	~1.4MB
Dependencies	Node.js 18+	None
Browser profile	Isolated (Puppeteer)	Real profile (Extension mode)

---

🛠 22 MCP Tools

All tools auto-detect the best backend (CDP → Extension fallback):

Tool	Description
chrome_list_tabs	List all open tabs
chrome_get_tab	Get detailed tab info by ID
chrome_create_tab	Open a new tab
chrome_close_tab	Close a tab
chrome_navigate	Navigate tab to URL
chrome_reload	Reload with optional cache bypass
chrome_evaluate_js	Execute JavaScript in tab
chrome_get_page_content	Full page HTML or text
chrome_screenshot	Capture visible tab as JPEG/PNG
chrome_query_selector	Find elements by CSS selector
chrome_click	Click element by selector
chrome_type_text	Type text into input fields
chrome_get_cookies	Retrieve cookies
chrome_set_cookie	Set a cookie
chrome_delete_cookies	Delete cookies
chrome_inject_css	Inject custom CSS
chrome_wait_for	Wait for element to appear
chrome_pdf	Export page as PDF (CDP only)
chrome_emulate_device	Mobile/tablet emulation (CDP only)
chrome_get_console_log	Console output (CDP only)
chrome_status	Bridge status & diagnostics
chrome_batch	Execute multiple commands in sequence

---

🚀 Quick Start

Option A: Extension Bridge Mode (recommended)

Works on any Chrome profile without restarting Chrome.

1. Start the bridge:

antigravity-chrome-bridge.exe

2. Install the extension:

1. Open chrome://extensions/
2. Enable "Developer mode"
3. Click "Load unpacked" → select chrome_extension/ folder
4. The popup should show "Connected" ✅

Option B: CDP Direct Mode

For headless automation and full CDP access.

1. Start Chrome with debug port:

& "C:\Program Files\Google\Chrome\Application\chrome.exe" --remote-debugging-port=9222

2. Start the bridge:

antigravity-chrome-bridge.exe

The bridge auto-detects CDP and connects directly.

---

🔌 MCP Configuration

Add to your MCP client configuration:

{
  "mcpServers": {
    "chrome_bridge": {
      "command": "/path/to/antigravity-chrome-bridge",
      "args": []
    }
  }
}

---

🏗 Building from Source

Prerequisites

• CMake 3.20+
• C++17 compiler (GCC 8+, Clang 7+, MSVC 2019+)

Linux / macOS

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(nproc)

Windows (MSVC)

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --config Release

Cross-compile for Windows (WSL + MinGW)

bash build.sh

Output: build-win64/antigravity-chrome-bridge.exe

---

🔧 Architecture

The MCP protocol is the native core — not a wrapper around REST APIs.

AI Agent ←─ stdio JSON-RPC ─→ MCPServer
                                  │
                    ┌─────────────┼─────────────┐
                    ▼                             ▼
              CDPClient                    ExtensionBridge
           (WebSocket:9222)              (HTTP Server:13371)
                    │                             │
                    ▼                             ▼
              Chrome CDP                  Chrome Extension
           (debug port)               (background.js polling)

Two backends, one interface:

• CDP mode connects via WebSocket to Chrome's DevTools debug port. Supports PDF, device emulation, console logs.
• Extension mode uses a Chrome Extension that polls an embedded HTTP server. Works with any Chrome profile without restart.

Tools operate directly on CDP/Extension engines — zero intermediate HTTP hops within the process.

---

📂 Project Structure

antigravity-chrome-bridge/
├── src/
│   ├── main.cpp           # Entry point: MCP stdio + HTTP bridge thread
│   ├── mcp_core.h/cpp     # JSON-RPC 2.0 protocol engine
│   ├── mcp_tools.h/cpp    # 22 tool definitions & handlers
│   ├── mcp_resources.h/cpp # Live MCP resources
│   ├── cdp_client.h/cpp   # Chrome DevTools Protocol WebSocket client
│   ├── ext_bridge.h/cpp   # Extension HTTP bridge + command queue
│   ├── ws_client.h/cpp    # Minimal RFC 6455 WebSocket client
│   └── config.h           # Constants & configuration
├── chrome_extension/
│   ├── manifest.json      # Manifest V3
│   ├── background.js      # Service worker (16 command handlers)
│   ├── popup.html         # Glassmorphism status popup
│   └── popup.js           # Popup state manager
├── legacy/                # Archived Python v1
├── CMakeLists.txt         # Build system
├── build.sh               # WSL cross-compile script
├── LICENSE                # Apache 2.0
└── README.md

---

🤝 Contributing

Contributions are welcome! Please see CONTRIBUTING.md for guidelines.

🔒 Security

For security concerns, please see SECURITY.md.

📄 License

This project is licensed under the Apache License 2.0 — see the LICENSE file for details.