Licences and credits
Last updated 17 October 2026
Chessmoose is built on the generous work of the open chess community. Thank you to everyone below.
Chess engine
Stockfish 19
The analysis board, Game Review, bots and endgame trainer use Stockfish, by the Stockfish developers. It is free software under the GNU General Public License v3. It runs as a separate program in your browser, compiled to WebAssembly by the stockfish.js project (version 19.0.1). The full source code is available at github.com/official-stockfish/Stockfish and github.com/nmrugg/stockfish.js. A copy of the exact engine files we serve is available on request.
Older browsers fall back to Stockfish 11 (asm.js build), under the same licence.
Data
- Puzzles: 803,717 puzzles from the Lichess puzzle database, released under CC0.
- Master opening statistics: games from the Lichess Elite Database, compiled from Lichess games released under CC0.
- Over-the-board games: tournament games broadcast on Lichess since 2020, from the Lichess broadcast database, released under CC0.
- Opening names: the lichess-org/chess-openings list, released under CC0.
- Player directory: names, federations, titles and ratings from the FIDE rating list. Chessmoose is not affiliated with FIDE.
Design
- Chess pieces: the “cburnett” set by Colin M.L. Burnett, under the GNU GPL v2 or later.
- Fonts: Manrope by Mikhail Sharanda and Fraunces by Undercase Type, both under the SIL Open Font License 1.1. They are served from chessmoose itself.
- Country flags: flag-icons by Panayiotis Lipiridis, under the MIT License (Copyright © 2013 Panayiotis Lipiridis).
- Icons and everything else: made for Chessmoose.