ReplayChess

ReplayChess is a free, open-source chess platform where chess history is something you play rather than watch. Pick one of 50+ legends, from Morphy and Capablanca to Kasparov and Carlsen, choose a famous game and start from its critical position. Play it out against a friend through a private invite link, a rating-matched opponent with live clocks, or Stockfish running as WebAssembly in your browser at four strengths. Afterwards you get a match rate against the original moves, a marker at the first move where you diverged, and a practice mode to retry the position. There is also an ECO-coded encyclopedia of 3,600+ openings, each playable from its resulting position, plus tournaments. Free with no ads; a Player plan ($4.99/month) unlocks the full catalogue. MIT-licensed on GitHub, built with Next.js 15, React 19, Prisma, Socket.IO and Stockfish WASM.