Frequently asked questions

Three steps, all on the dashboard. Connect: pick Chess.com or Lichess and enter your username. Sync: the site fetches your public games, oldest first, and you can stop it whenever you like. Analyse: Stockfish reviews every move, and the pages fill in as the analysis progresses.

Everything else is in the header menus: your portrait, your openings, your opening, tactical and endgame mistakes, and puzzles taken from your own games.

No account is needed to get started. The site only reads the games Chess.com and Lichess already publish for everyone: it will never ask for your Chess.com or Lichess password, and you can analyse any public username.

No. Your browser downloads your games straight from Chess.com or Lichess, the engine runs on your machine, and your games and their analyses stay in your browser's storage. They are not sent to any server. The details are on the Privacy page.

Under a second per game on a recent computer: about two minutes for 150 games, a quarter of an hour for a thousand. The first run downloads the engine (7 MB), once.

The analysis works backwards, from recent games to older ones: you can stop it as soon as the period you care about is covered.

The analysis stops, and nothing already done is lost. When you come back, it resumes with the games still missing. To fetch your new games, click “Sync”: if you had already started an analysis, they are analysed right away.

Because they are stored in the browser where they were made, and nowhere else. Another browser, another device or a private window starts from scratch.

A score out of 100 derived from what each move cost compared with the best move: 100 for perfect play, 50 if you lose the equivalent of a pawn every move. Your opponent's is computed the same way, so you compare yourself with players of your own level.

The site analyses thousands of positions in your browser, so it works at a modest depth — measured so that the mistakes it keeps are the same as at a much greater depth. A few centipawns of difference with a site's analysis are normal, and don't change what matters: the moves that cost you points.

From your own mistakes. A position becomes a puzzle when it had only one good solution, or when a mate in two to five was missed there. You replay the opponent's move that leads to it, then it's your turn to find it.

The opening is different: the position of your first real mistake becomes a puzzle if one or two answers clearly stand out. You don't need the best move there, just a sound one — book moves are always accepted.

On the dashboard, the Delete button of the Profile card erases the games and analyses of the connected account. Log out deletes nothing. Clearing this site's data in your browser settings erases everything.

Yes, every page adapts to it. The analysis is slower there and pauses when the screen turns off; for a first analysis of hundreds of games, a computer is more comfortable.