A sleek and intelligent chess experience powered by cutting-edge web technology.
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Fully optimized for Desktop, Tablet, and Mobile devices
Overview • Features • Screenshots • Tech Stack • How to Play • Structure • Contributing
SiChess is a professional-grade chess web application that brings desktop-class performance to your browser. Built with React 19 and powered by Stockfish 17.1 running in WebAssembly, it delivers lightning-fast move calculation, deep position analysis, and a beautifully crafted user experience.
Perfect for players of all levels—from beginners taking their first steps to masters analyzing complex positions and enthusiasts watching high-level engine battles.
- Stockfish 17.1 via WebAssembly: Zero-latency move calculation running entirely in your browser
- 26 Calibrated Difficulty Levels: From 250 ELO (Beginner) to 3200 ELO (Ultimate)
- Intelligent Error Modeling: Human-like play at lower levels with phase-aware mistakes (opening/middlegame/endgame)
- Dual-Engine Architecture: Separate engines for gameplay and background evaluation ensure smooth performance
- 🛡️ Defensive: Safety-first positional chess with castling priority and avoiding complications
- ⚔️ Aggressive: Tactical fireworks with preference for checks, captures, and sacrifices
- ⚖️ Balanced: Optimal strategic play without style bias
- Deep Game Review: Analyze every position with configurable engine depth (up to 22 ply)
- 10-Tier Move Classification System:
- 💎 Brilliant (sacrifices), ⭐ Great (underpromotions)
- ✅ Best, 🟢 Excellent, Good moves
⚠️ Inaccuracies, ❌ Mistakes, ❗ Misses (winning chances lost)- 💥 Blunders
- Accuracy Metrics: Winning probability-based accuracy calculation for both players
- Visual Game Flow Chart: Track evaluation swings throughout the game
- Live Move Feedback: Real-time best move suggestions and position evaluation
- PGN Analysis: Import games from other platforms for instant analysis
- Choose your color (White, Black, or Random)
- Adjustable difficulty from beginner to superhuman
- Hints and takebacks to help you learn
- Handicap Mode: Remove pieces (Queen, Rooks, Bishops, Knights, Pawns) for odds games
- Local multiplayer on the same device
- Optional piece rotation for over-the-board feel
- Custom time controls for blitz to classical games
- Watch two engines battle with independent difficulties and styles
- Pause and navigate through the game
- Perfect for studying engine lines or entertainment
- Chess960 (Fischer Random): 960 starting positions with proper castling rules
- Time Controls: None, 10-minute, or fully custom settings (1-99 minutes per side)
- Adaptive Layouts: Intelligent portrait (mobile) and landscape (desktop/tablet) interfaces
- Smooth Animations: Piece sliding with castling coordination and capture fade-outs
- Promotion Interface: Visual piece selection tray with intelligent positioning
- High-Quality Audio: Distinct sounds for moves, captures, castling, checks, and game events
- Modern Dark Theme: Eye-friendly design with glassmorphism effects
- Evaluation Bar: Real-time position advantage visualization
- Legal Move Indicators: Visual guides for valid moves and captures
- King Check Highlighting: Instantly see when kings are in danger
- Toggle evaluation bar, move feedback, and hints
- Enable/disable takebacks (undo moves)
- Piece rotation for PvP games
- Adjustable time controls
- Chess960 variant toggle
- Persistent settings across sessions
- Import: Load games from Chess.com, Lichess, or any PGN file
- Export: Share games with full metadata (Event, Site, Date, Result, Time Control, Termination)
- Web Share API: Instant sharing on mobile devices
Landing • Setup • Gameplay
Full-featured layout with move history sidebar and analysis tools
- React 19.2 - Latest React with concurrent features
- TypeScript 5.8 - Type-safe development
- Vite 6.2 - Lightning-fast build tooling
- Tailwind CSS - Utility-first styling
- Stockfish.js (WebAssembly) - World's strongest chess engine
- chess.js 1.4 - Move generation and validation
- Custom UCI Implementation - Direct Stockfish communication via Web Workers
- Dual-Engine Design: Separate workers for gameplay and evaluation prevent blocking
- Queue-Based Task Management: Prioritized engine requests with graceful error handling
- Multi-PV Analysis: Evaluates multiple candidate moves for realistic human play
- Phase-Aware Error Modeling: Different mistake probabilities for opening/middlegame/endgame
- Reactive State Management: Custom hooks for complex game state
- Service Layer Pattern: Clean separation of concerns (engine, analysis, sound)
- Select Mode: Choose PvC (vs Computer), PvP (2 Player), Spectate (Engine Battle), or Analyze (Import PGN)
- Configure: Set names, colors, difficulty, and time controls
- Play: Drag-and-drop or click-to-move pieces
- Analyze: After the game, review with move classifications and best move suggestions
- ⚙️ Settings - Customize features • 💡 Hint - See best move • ↩️ Undo - Take back moves
- 🏳️ Resign - End game • ⏸️ Pause - Freeze spectator mode • 📤 Share - Export PGN
- Move Navigation: Click move list or use chevrons to browse history
- Analysis Mode: Deep review with accuracy stats, game flow chart, and move classifications
- Time Controls: Choose None, 10 min rapid, or custom times (1-99 min per side)
- Hints & Feedback: Real-time evaluation and best move arrows (can be toggled)
sichess/
├── public/
│ ├── stockfish.js # Stockfish engine
│ ├── stockfish.wasm # WebAssembly binary
│ └── assets/
│ ├── pieces/ # Chess piece images
│ └── sounds/ # Game audio files
├── components/ # React components
│ ├── Board.tsx # Chess board with drag-drop
│ ├── GameOverModal.tsx # End game interface
│ ├── GameReviewModal.tsx # Analysis summary
│ ├── NameInputModal.tsx # Game setup
│ └── ... # 20+ specialized components
├── hooks/
│ ├── useChessGame.ts # Core game state logic
│ └── useViewport.ts # Responsive layout
├── services/
│ ├── chessEngine.ts # Stockfish integration
│ ├── analysisService.ts # Game analysis logic
│ └── soundManager.ts # Audio playback
├── App.tsx # Main application component
├── types.ts # TypeScript definitions
├── index.html
├── index.tsx
├── vite.config.ts
└── package.json
Lower difficulty levels use a sophisticated error model with phase-aware mistakes, weighted error selection, and multi-PV candidate evaluation to simulate realistic human play.
Play styles influence move selection beyond raw evaluation—Aggressive prioritizes attacks, Defensive favors safety, and Balanced uses pure engine logic.
Two independent Stockfish workers prevent UI blocking: gameEngine for high-priority moves and evalEngine for background analysis.
Smooth piece transitions, coordinated castling, capture fade-outs, and intelligent promotion tray positioning for a polished experience.
- Custom UCI protocol implementation with Web Workers
- Winning probability model for move classification (sigmoid function)
- Robust PGN parsing with Chess960 support
- Complex state management with history navigation
- Responsive design with adaptive portrait/landscape layouts
- React 19 concurrent rendering for 60 FPS gameplay
Contributions are welcome and appreciated — they help the project grow and improve.
Because this project uses the GPL-3.0 License, any contributions must also remain open-source under the same license.
- Fork the repository
- Create a feature branch →
git checkout -b feature/AmazingFeature - Commit your changes →
git commit -m "Add AmazingFeature" - Push the branch →
git push origin feature/AmazingFeature - Open a Pull Request
- 🌐 Multi-language support (i18n)
- 🎨 Additional piece sets & board themes
- 📊 Opening book with ECO classification
- 💾 Cloud save, profile & history sync
- 🏆 Puzzle / tactics trainer
- 📈 Game analytics & visual statistics
- ♟️ Online multiplayer (WebRTC/WebSockets)
Bug Reports: Open an issue with description, reproduction steps, expected behavior, and device/browser info.
This project is licensed under the GNU General Public License v3.0 (GPL-3.0).
By participating in this project (including submitting pull requests), you agree that your contributions will be distributed under the same GPL-3.0 license.
See the LICENSE file for full legal terms.
- Stockfish Team - For the incredible open-source chess engine
- chess.js Contributors - For reliable move generation
- Chess.com & Lichess - For UI/UX inspiration and design patterns
Siddhant - GitHub Profile
Email: siddhantdigraje77@gmail.com
Project Link: https://github.com/siddhantdg/sichess
Built with ❤️ using React, TypeScript, and Stockfish
⭐ Star this repo if you find it useful! ⭐