Acknowledgements and licences

Chesspedition stands on open-source software, open data and freely licensed artwork. This page lists each one, what we use it for, its licence and where to get its source.

• Stockfish 19

  The chess engine behind every evaluation and move label. It runs as its own program: in your browser as a separate worker (the WebAssembly build stockfish.js 19.0.1, unmodified) and on our servers as a separate process. It is never part of our own code.

  GNU General Public License v3.0

  Stockfish sourceSource of the exact browser build we serveLicence text

• cm-chessboard

  The board you see and move pieces on.

  MIT

  Source

• chess.js

  Chess rules: legal moves, notation and game records.

  BSD 2-Clause

  Source

• Chess pieces

  The standard piece set by Colin M.L. Burnett (Cburnett) and Rfc1394 from Wikimedia Commons, as adapted by shaack for cm-chessboard.

  Creative Commons Attribution-ShareAlike 3.0

  Wikimedia CommonsLicence

• Lichess open data

  Opening names come from the Lichess opening list, and our puzzles are chosen from the Lichess puzzle database, which was made from games played on Lichess. Lichess has dedicated both to the public domain. Thank you, Lichess.

  CC0 1.0 (public domain)

  lichess-org/chess-openingsLichess puzzle databaseLichess open database

• Typefaces

  Bricolage Grotesque, Figtree and JetBrains Mono, served from our own site.

  SIL Open Font License 1.1

  Open Font License

Chesspedition is not affiliated with Chess.com or Lichess. Game data is read from their public APIs at your request.