Credits & licences

Runs in your browser for the engine analysis after a tactics or calculation task: the lite, single-threaded WebAssembly build of Stockfish.js by Nathan Rugg (npm package stockfish 18.0.8), served from this site.

Source code: official-stockfish/Stockfish and nmrugg/stockfish.js. Stockfish is free software: you may copy, change and share it under the GPL. Stockfish also checks every drill position before it goes live.

Games and the Lichess puzzle database, from database.lichess.org. The tactics puzzles and their opening tags come from it; so do the games of the Lichess drill positions.

Games between strong players on Lichess, collected at database.nikonoel.fr: a source of drill positions.

Master games from theweekinchess.com: a source of drill positions.

By Armando Hernandez Marroquin. The SVG files come from the Lichess source code (lila, public/piece/merida; licence as listed in lila’s COPYING.md). Changed for EvalChess: solid black and white instead of the shaded fill, and a thin white outline for the hatched squares. The changed files, which are their own source, are at /pieces/merida/.

By Colin M.L. Burnett, as bundled with react-chessboard (licence as listed in lila’s COPYING.md; the original drawings are on Wikimedia Commons).

The board, by Ryan Gregory: Clariity/react-chessboard.

Move rules and notation, by Jeff Hlywa: jhlywa/chess.js.

The FSRS spaced-repetition scheduler: open-spaced-repetition/ts-fsrs.

The web framework this site runs on.