Next-Generation AI Chess Analysis
Professional Analysis for Chrome & Safari

ChessSight (formerly Mephisto) is a high-performance browser extension that brings engine-grade chess analysis to your favorite chess websites.

Unlike basic evaluation tools, ChessSight integrates Stockfish 16+ directly into your browser via WebAssembly (WASM) for near-instant analysis without server latency, while also offering a local backend mode for leveraging your hardware's full power.

• 🚀 Instant Analysis: Real-time evaluation using optimized WASM Stockfish binaries.
• 🌐 Universal Support: Seamlessly works on Chess.com, Lichess, and BlitzTactics.
• 🛡️ Privacy First: Runs entirely locally in your browser. No game data is sent to external servers unless using the optional LLM chat.
• 🤖 AI Assistant: Integrated Chat interface connecting to LLMs (Ollama/OpenAI) to explain positions in plain English.
• 🍏 Native Safari App: Fully signed and native Safari Web Extension for macOS users.

ChessSight operates on a modular architecture designed for performance and isolation.

graph TD
    subgraph Browser Context
        CS[Content Script] -->|Detects Board/Moves| BG[Background Service]
        UI[Popup / Sidebar UI] -->|User Commands| BG
        BG -->|Orchestrates| WE[WASM Engine Worker]
        WE -->|Stockfish 16| BG
    end

    subgraph "Optional Local Backend"
        BG -.->|WebSocket/HTTP| API[Python FastAPI Server]
        API -->|Subprocess| SE[Stockfish System Binary]
        API -.->|REST| O[Ollama / OpenAI API]
    end

    classDef browser fill:#e1f5fe,stroke:#01579b,stroke-width:2px;
    classDef server fill:#f3e5f5,stroke:#4a148c,stroke-width:2px;
    class BG,CS,UI,WE browser;
    class API,SE,O server;

1. Go to the Releases Page (link will work once published).
2. Download ChessSight-v2.1.0.zip.
3. Unzip the file.
4. Open chrome://extensions/
5. Enable Developer mode (top right toggle).
6. Click Load unpacked and select the unzipped ChessSight folder.

1. Build the native wrapper:

   ./build-safari.sh
   open "Safari/ChessSight/ChessSight.xcodeproj"

2. In Xcode, select the ChessSight (macOS) scheme and run (Cmd+R).
3. Enable the extension in Safari Settings > Extensions.

The project is structured as a modern monorepo:

Ensure you have Node.js 18+.

No build steps required! just follow the installation instructions above.

If you want to run the heavy-duty Python analysis engine:

# Install backend dependencies
cd backend
pip install -r requirements.txt

# Run backend server
./start.sh

We welcome engineering contributions. Please check docs/CONTRIBUTING.md for our code standards and pull request process.

MIT License. See LICENSE for details.