ReplayChess

ReplayChess is a free, open-source chess platform where chess history is something you play rather than watch.

Every chess fan knows the moment: the video pauses at the critical position, you find the winning move, and then the narrator plays it for you. ReplayChess is the other half of that experience. Pick one of 50+ legends, from Morphy and Capablanca to Kasparov and Carlsen, choose a famous game and start from its decisive position. Play it out for real 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. When the game ends 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 at $4.99/month unlocks the full catalogue. MIT-licensed on GitHub (replay-chess/chess-battle-turbo), built with Next.js 15, React 19, Prisma, Socket.IO and Stockfish WASM.