What TheoryChess is
TheoryChess is an opening trainer for people who would rather learn openings by playing them than by memorising lists of moves. You pick an opening and a variation and make the moves on the board yourself; the moment you leave theory you see it, and you learn the right continuation.
The opening tree comes from the public lichess-org/chess-openings dataset. Moves are evaluated by the Stockfish chess engine, which runs directly in your browser.
What you can do
- Train: play a variation against the engine and see why each move is played.
- Quiz: find the next theory move in positions from an opening and track your score.
- Spaced repetition: lines you finish without a mistake come back just before you would forget them.
- Analysis: your quiz answers are broken down variation by variation, weakest first.
- Game report: your latest lichess or Chess.com games are compared with opening theory; the places you leave it most, and the lines to study, come first.
- Opponent prep: from an opponent’s public games, see which openings they play and where they leave the theory, and find the lines to study against them.
Game reports and opponent prep are Premium features, free for everyone during the beta.
Training and quizzes work without an account. To keep your progress, favourites and quiz scores, sign in with your Google account.
Who makes it
TheoryChess is built and run by Hasan Süzen as an individual. There is no company behind it.
Independence
TheoryChess is not affiliated with or endorsed by lichess.org, Chess.com, FIDE or the Stockfish developers. Those names appear only to credit the open-source data and software the site uses, and the source of the public game data game reports are made from.
Contact
For suggestions, bug reports or questions, write to [email protected].