Acknowledgements

Last updated October 17, 2026

Slate Chess is built with care, and with the help of other people's work. This page credits the open-source software, artwork and marks used by the Slate Chess website and by chessmen, our open-source web chessboard. Acknowledgements for components inside the app are included in the app itself.

chessmen

The animated board on this site is chessmen, Copyright 2026 Linu Alex, licensed under the Apache License 2.0. Source: github.com/slate-chess/chessmen. See also its LICENSE, NOTICE and third-party notices.

chess.js

chessmen bundles chess.js 1.4.0 by Jeff Hlywa and contributors (BSD 2-Clause), which provides the chess rules and PGN reading.

Copyright (c) 2025, Jeff Hlywa (jhlywa@gmail.com)
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

Modern Staunton pieces

After the chess pieces by Colin M. L. Burnett (Wikimedia Commons, 2006), used under the BSD 3-Clause licence and redrawn by Slate Chess so fills and lines take colours separately.

Copyright (c) 2006, Colin M. L. Burnett
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the
   following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
   following disclaimer in the documentation and/or other materials provided with the distribution.
3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
   products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Classic Staunton pieces

After Chess Mérida by Armando Hernández Marroquín (1998), via the chess_merida_unicode project, released under the Unlicense (public domain dedication), and adapted by Slate Chess for fill and line colours.

Trademarks

Apple, the Apple logo, iPhone, iPad, Mac, Apple TV and TestFlight are trademarks of Apple Inc., registered in the U.S. and other countries. App Store is a service mark of Apple Inc. Lichess is a free, open-source chess site and is not affiliated with Slate Chess. Stockfish is named only to identify an opponent in our engine tests. Other names are the property of their owners.