For AI agents: the documentation index is at https://www.chessigma.com/llms.txt, and this page is available as Markdown at https://www.chessigma.com/developers.md.
v1.0.0 A free API for chess game analysis. Submit a game, read its analysis, calculate rating changes, and fetch the daily puzzle. No API key, no signup, no paywall.
Base URLhttps://www.chessigma.com/public-api/v1
No API key or account. Every endpoint is open.
A shared global limit. Over it returns 429.
Engine analysis runs in the browser. Submit a game, then open its URL to analyze.
Please attribute Chessigma when you use the API. By using it you accept the terms of service.
Submit a game, then open the returned URL to view and analyze it.
curl -X POST https://www.chessigma.com/public-api/v1/game \
-H "Content-Type: application/json" \
-d '{"pgn": "[White \"Alice\"]\n[Black \"Bob\"]\n[Result \"1-0\"]\n\n1. e4 e5 2. Nf3 Nc6 1-0"}'
/game
Submit a game (PGN) for analysis
Stores a chess game and returns a URL to view and analyze it on Chessigma. Duplicate games (same players + date) are deduplicated and return the existing gameId.
/game/{gameId}
Retrieve analysis for a submitted game
Returns game metadata and analysis. Because analysis runs client-side, this returns data only if a user has already opened the game page and triggered analysis. Only games submitted via this public API are readable here.
/elo-calculator
Compute an Elo rating change for a single game
Pure arithmetic. Returns the new rating, point change, and expected score.
/daily-puzzle
Get the daily chess puzzle
Returns the single daily puzzle for today, or a past date via ?date=YYYY-MM-DD. Returns exactly one puzzle. The full puzzle database is not exposed.
Full request and response schemas are in the OpenAPI spec.
You do not always need the API. These URLs drop a user straight into a live, client-side tool. Standardize on fen for positions and pgn for games. URL-encode the value.
/tools/analysis?fen=<FEN>
Opens the live analysis board on a position.
/tools/analysis?pgn=<PGN>
Loads a game for move-by-move replay and analysis.
/tools/next-move?fen=<FEN>
Finds the engine's best move for a position.
/tools/analysis/editor?fen=<FEN>
Opens the board editor on a position.
/games/<gameId>?move=<n>
Jumps to a specific move in a submitted game.
Chessigma publishes a machine-readable discovery surface so AI agents can find and use it.
/openapi.json: the OpenAPI 3.1 contract./.well-known/api-catalog: RFC 9727 catalog./.well-known/agent-skills/index.json: the agent skill index.