Chessigma API

Chessigma released version 1.0.0 of its public chess analysis API, a free interface at https://www.chessigma.com/public-api/v1 that requires no API key, signup, or paywall. The API offers four endpoints — /game to submit a PGN for analysis, /game/{gameId} to retrieve analysis, /elo-calculator for Elo rating arithmetic, and /daily-puzzle for one daily puzzle — under a shared global rate limit that returns HTTP 429 when exceeded, with engine analysis running client-side in the browser. Chessigma also published machine-readable discovery files for AI agents, including an OpenAPI 3.1 spec at /openapi.json, an RFC 9727 catalog at /.well-known/api-catalog, an agent skill index at /.well-known/agent-skills/index.json, and an llms.txt documentation index.

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 URL https://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 https://www.chessigma.com/tos . 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"}' 201 Created { "gameId": "f222a278-...", "url": "https://www.chessigma.com/games/f222a278-...", "status": "submitted" } /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 https://www.chessigma.com/openapi.json . 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.