ReplayChess

ReplayChess is a free, open-source chess platform where you start from the critical position of a famous game and play it out for real: against a friend via a private link, a rating-matched opponent with live clocks, or Stockfish running as WebAssembly in your browser. Afterwards you get a match rate against the grandmaster's moves and the exact move where you diverged. 50+ legends from Morphy to Carlsen, an ECO encyclopedia of 3,600+ playable openings, tournaments, and a practice mode. Built with Next.js 15, React 19, TypeScript, Tailwind, Prisma on Neon Postgres, Clerk auth, Socket.IO and Stockfish WASM; MIT-licensed on GitHub.