Chessigma
v1.0.0

Chessigma API

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.

OpenAPI specAPI catalogMCP server

Base URLhttps://www.chessigma.com/public-api/v1

Using the API

No authentication

No API key or account. Every endpoint is open.

30 requests / minute

A shared global limit. Over it returns 429.

Compute-free

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.

Quickstart

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" }

Endpoints

POST/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.

GET/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.

GET/elo-calculator

Compute an Elo rating change for a single game

Pure arithmetic. Returns the new rating, point change, and expected score.

GET/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.

Linkable routes

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.

Analyze a position/tools/analysis?fen=<FEN>

Opens the live analysis board on a position.

Analyze a full game/tools/analysis?pgn=<PGN>

Loads a game for move-by-move replay and analysis.

Best next move/tools/next-move?fen=<FEN>

Finds the engine's best move for a position.

Set up a position/tools/analysis/editor?fen=<FEN>

Opens the board editor on a position.

View a submitted game/games/<gameId>?move=<n>

Jumps to a specific move in a submitted game.

For AI agents

Chessigma publishes a machine-readable discovery surface so AI agents can find and use it.

  • /developers/mcp: the MCP server, which brings Chessigma's chess tools to Claude, ChatGPT and other AI assistants.
  • /openapi.json — the OpenAPI 3.1 contract.
  • /.well-known/api-catalog — RFC 9727 catalog.
  • /.well-known/agent-skills/index.json — the agent skill index.