ReplayChess is a free, open-source chess platform for people who want to play chess history rather than browse it. Chess history has always been passive: videos, books, databases. You watch a legendary game, pause at the critical moment, find the winning move in your head, and then the video moves on. In a real game, finding the move is only half the job. You still have to convert the position, and that is much harder than it looks.

ReplayChess fixes that. Pick a legend such as Morphy, Capablanca, Tal, Fischer, Kasparov or Carlsen, jump into one of their famous games at its decisive position, and play it out. You can play against a friend through a private invite link, against a matched opponent from the ELO queue, or against Stockfish running entirely in your browser at one of four strengths from Easy to Expert (around 2200). When the game ends you get a move-by-move comparison with the original: your match rate against the grandmaster's line, and the exact move where you diverged. A practice mode lets you replay the position against the engine as many times as you like.

There is also an openings encyclopedia of more than 3,600 ECO-coded openings, every one of them playable from the resulting position, with the moves, the FEN, and narrated ideas on the key lines. Real-time multiplayer includes ELO-based matchmaking with time controls, private challenges, and tournaments. Distinct sounds mark moves, captures, checks, castling and time warnings. The whole thing installs as a PWA on phone and desktop.

Who it is for: club and online players who pause chess videos to find the winning move and want to actually play the position out; coaches who want training positions with a real opponent; friends who want to settle who plays more like Tal under pressure; and developers curious about a real-time multiplayer chess app built with Next.js 15, React 19, Socket.IO, Prisma and Stockfish compiled to WebAssembly. The source is MIT-licensed on GitHub.

ReplayChess is free to play. A Player plan at $4.99 per month or $50 per year unlocks the full legend and opening catalogue. There are no ads. A no-login demo is available at playchess.tech/try.