Third-party licenses

FreeChessTrainer.org uses the following third-party software and artwork. We are grateful to their authors and contributors.

Stockfish and Stockfish.js

The locally hosted chess engine is Stockfish, compiled to JavaScript by Niklas Fiekas and other Stockfish.js contributors. Stockfish and Stockfish.js are distributed under the GNU General Public License, version 3.

• GNU GPL version 3 license text
• Stockfish.js source code
• Stockfish source code

Wikipedia chess pieces

The chess-piece artwork was created by Wikimedia Commons user Cburnett. The author offers the artwork under multiple licenses; this site uses the 3-clause BSD license option.

• BSD license and attribution notice
• Original artwork and authorship

Browser libraries

The trainer loads these libraries from public content-delivery networks:

• chessboard.js 1.0.0 — MIT License
• chess.js 0.10.3 — 2-clause BSD License
• jQuery 3.5.1 — MIT License
• jQuery UI 1.13.2 — MIT License
• jQuery UI Touch Punch 0.2.3 — MIT License option

Chess opening data

Opening names and move sequences are derived from the Lichess chess-openings dataset, released under the CC0 Public Domain Dedication.