ReplayChess is a free, open-source (MIT) chess platform where you replay famous games from their critical position against real opponents or Stockfish. Pick a legend, jump into one of their games at the decisive moment, and try to find the moves they found; afterwards you get a match rate against the original and a marker at the first move where you diverged.

Features

• 50+ legends from Morphy to Carlsen with playable famous positions
• 3,600+ ECO-coded openings, each playable from its resulting position
• Real-time multiplayer with rating-based matchmaking, private challenge links and tournaments
• Stockfish compiled to WebAssembly, four strengths up to ~2200
• Post-game divergence report and practice mode; installs as a PWA

Built with Next.js 15, React 19 (React Compiler), TypeScript, Tailwind v4, Prisma + Postgres, Clerk, Socket.IO, Stockfish WASM. Web app on Vercel, websocket server on EC2. Repo: github.com/replay-chess/chess-battle-turbo

Pricing Free to play; Player plan $4.99/month or $50/year unlocks the full legend and opening catalogue.