ChessGrader / Licenses & attribution
Open Source Licenses & Attribution
ChessGrader is built on open-source chess software, some of it copyleft. This page names every component, its licence, and where to get its source — and states plainly who owns the trademarks we mention.
Independence
ChessGrader is not affiliated with, endorsed by, or sponsored by Chess.com, Lichess.org, the Stockfish developers, or any chess federation. Names and logos belonging to those organisations are used descriptively, to identify which platforms ChessGrader works with. All trademarks are the property of their respective owners.
Stockfish
The analysis engine is Stockfish 17.1 (lite NNUE, single-threaded, compiled to WebAssembly), served from this site and executed in your browser. Stockfish is copyright the Stockfish developers (see the AUTHORS file in the source) and is licensed under the GNU General Public License, version 3.
- Licence text as distributed with the engine files: /engine/COPYING.txt
- Authors and attribution: /engine/AUTHORS.txt
- Upstream source: github.com/official-stockfish/Stockfish
- The exact WebAssembly build served here comes from the unmodified npm package stockfish@17.1.0, whose source is published at github.com/nmrugg/stockfish.js. We have made no modifications to it.
Written offer: for as long as we distribute these engine binaries, we will provide the complete corresponding source code for the version served here, under the terms of the GPL, to anyone who asks at contact@chessgrader.com.
Chessground
The interactive board is chessground, developed by the Lichess team and licensed under the GNU General Public License, version 3 or later. Source: github.com/lichess-org/chessground. Chessground is used unmodified.
Other components
- chess.js — move generation, validation, PGN parsing. BSD 2-Clause licence. github.com/jhlywa/chess.js
- React and Next.js — application framework. MIT licence.
- Manrope — typeface by Mikhail Sharanda, SIL Open Font License 1.1, self-hosted.
Game data
Games are retrieved by your browser from the public interfaces of Chess.com and Lichess, or supplied by you as PGN. The sequence of moves in a chess game is not itself copyrightable. Player names, ratings, and other header data come from the platform’s public record and are shown as published. Demonstration games shipped with the site are publicly played games, presented without third-party annotations.
Reporting a problem
If you believe something on this site infringes your copyright, trademark, or licence terms — including any attribution we have failed to make — email contact@chessgrader.com with the details and we will act on it promptly.
See also our Terms of Use and Privacy Policy.