What it is
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. You start from the critical position of a famous game and play it out for real, against a friend, a rated opponent, or Stockfish in your browser, and afterwards you see exactly where your moves left the grandmaster's line.
What you can do
- Play as a legend. Fifty-plus players from chess history, from Morphy and Anderssen through Fischer and Kasparov to Carlsen and Praggnanandhaa, each with a profile and a set of famous games whose decisive positions are ready to play.
- Play from any opening. An ECO-coded encyclopedia of 3,600+ openings. Every one is playable from its resulting position, so you practise the middlegames your repertoire actually produces instead of replaying the first ten moves.
- Real opponents, real clocks. Rating-based matchmaking with time controls, private challenge links that a friend can open without an account, and tournaments.
- Stockfish in the browser. The engine runs as WebAssembly on your device at four strengths, from Easy to roughly 2200.
- Divergence report. After each legend game you get a match rate against the original moves and a marker at the first move where you diverged, plus a practice mode to retry the position.
Who it is for
Club and online players in the 800 to 2000 range who follow chess history channels, coaches who want to hand a student a specific position and review the result, and developers curious about a working real-time multiplayer app in Next.js.
Pricing and source
Free to play, no ads. A Player plan at $4.99 a month or $50 a year unlocks the full legend and opening catalogue. The code is MIT-licensed on GitHub (replay-chess/chess-battle-turbo), built with Next.js 15, React 19, Prisma on PostgreSQL, Socket.IO and Stockfish WASM, and it installs as a PWA on phones and desktops.
