Licenses & Attributions

AxiomChess is an independent project. It is not affiliated with, sponsored by, or endorsed by Chess.com, Lichess, or the Stockfish project. Chess.com and Lichess are trademarks of their respective owners, used here only to identify those services.

Stockfish chess engine

Analysis is powered by Stockfish, running in your browser as an unmodified WebAssembly build of Stockfish.js 18 (the stockfish npm package, v18.0.5, “lite single” build). Stockfish is free software distributed under the GNU General Public License v3. The complete corresponding source code for the exact build we serve is available at github.com/nmrugg/stockfish.js (engine source: github.com/official-stockfish/Stockfish). Copyright © the Stockfish developers.

Board recognition (ONNX Runtime Web)

Scanning a game from video runs a small board-recognition model in your browser using ONNX Runtime Web v1.27.0, redistributed unmodified under the MIT License, © Microsoft Corporation (license text). The recognition model itself is ours, trained entirely on synthetic boards we generated — no third-party image dataset is used, and nothing you scan leaves your device.

Data sources

Game archives and player stats are fetched on demand from the Chess.com Published-Data API for the player you look up. We compute all evaluations, accuracy numbers, and move classifications ourselves with Stockfish — none are Chess.com's.
The opening explorer's “Masters” and “Lichess” tabs summarise the Lichess opening explorer — the masters (over-the-board) database and the Lichess games database respectively. Thanks to Lichess for keeping this data available. The “Your games” tab is computed on your own device from your own games and involves no third party.
Training puzzles are sourced from the Lichess puzzle database, released to the public domain under the CC0 1.0 dedication. Attribution isn't required by CC0 — we credit Lichess because the generosity deserves it.

Piece design & typography

The Signature Staunton piece set is our own rendering; its geometry derives from the classic chess piece designs by Colin M. L. Burnett (cburnett), published under GPL / CC BY-SA licenses. Our rendering of the piece set is likewise available under those same terms.
The interface typeface is Instrument Sans, licensed under the SIL Open Font License 1.1 and self-hosted with the app.

Open-source libraries

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