Chess AI: watch models play, or play yourself

Chess AI: when the moves are chosen by artificial intelligence

This is classic chess where large language models do the thinking. The tool shows the board and, at every step, asks an AI for a move: the model receives the position (FEN) and the full list of legal moves and returns its choice. You can simply watch two models play, or play against the AI yourself.

Two game modes

• AI vs AI — choose a model for white and black and watch them play. Pit different models against each other: GPT vs Claude vs Gemini.
• You vs AI — play yourself: click a piece, legal moves are highlighted, and the AI opponent replies with its move.

What the tool can do

• full chess rules: castling, en passant, pawn promotion, check, checkmate, stalemate, and draws;
• a provider and a modern model chosen separately for each side;
• a move log in UCI notation, a check highlight, sound, and save/load of a game;
• settings in a handy popup: mode, side, models, and the delay between moves.

You bring your own API key

To let a model think, add your own API key from one of the providers (OpenAI, Anthropic, or Google) in Settings. The key is stored only in your browser and is sent straight to the provider — we never store it. That way you control which model plays and what it costs.

Questions about chess AI

How strongly do the models play?
It varies. Language models are not dedicated chess engines, so this is more of an experiment: it is fun to see how logically different models handle a game. The rules are fully enforced by the built-in engine — an illegal move is impossible; if a model suggests an invalid move, the tool retries a few times and then picks a random legal one.

Where does my data go?
The whole game runs in your browser; only a move request goes to the server and is immediately forwarded to your chosen provider with your key. We store neither keys nor games.

This is one more tool in the section — all utilities are gathered on the online tools page.