Licenses

Stockfish

The game analysis runs Stockfish 19 (lite, single-threaded WebAssembly build, from the stockfish.js 19.0.1 package) in your browser. Stockfish is free software released under the GNU General Public License, version 3. It is served unmodified, as a separate program, from this site.

• License text (GPLv3)
• Where to get the source code
• Source code of this build (stockfish.js 19.0.1) and its neural network

chess.js

Move validation uses chess.js, Copyright (c) 2025, Jeff Hlywa, released under the BSD 2-Clause License (license text).