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.

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.
“How masters played here” uses the Lichess masters opening explorer. Thanks to Lichess for keeping this data available.
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.
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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