Stockfish + Claude
Find and understand your worst moves
Paste a chess.com game. The engine finds your three costliest moves, and you get a plain-English reason for each one, right next to the board.
1
Stockfish in your browser
Every position is evaluated locally in a Web Worker. No engine server, nothing to wait for in a queue.
2
Claude explains, with your key
Your three costliest moves get a short, plain-language reason and a better plan, pitched at your level. New explanations use your own Anthropic API key, which stays in your browser; each one is cached and shown to anyone who analyses the same position.
3
Grounded in the engine line
Explanations may only use the engine's own variation, so they can't invent moves that don't work.