Chess Methodica uses the Lichess Puzzle Database under CC0 and the Lichess chess-openings dataset under CC0-1.0. We acknowledge their contributors and do not claim ownership of these datasets or affiliation with Lichess, Chess.com or FIDE.
Browser analysis uses Stockfish.js 17.1 and Stockfish under GPL-3.0. The chess.js rules library retains its BSD license notice. Links below identify data sources, engine source and bundled license notices. Chess Methodica’s rating estimates are separate from the original dataset ratings and externally displayed account ratings.