Is ChessAnalyser really free?
Yes. Unlimited game reviews are free. The analysis runs on your device with the lite Stockfish NNUE build, so there is no paid engine service or analysis quota.
FAQ
Questions before the first move.
Do I need an account?
No sign-up is needed to analyze games or study openings. An optional account is planned so you can save your games and progress across devices.
Can I import Chess.com and Lichess games?
Yes. You can paste or upload standard PGNs, fetch Lichess games by URL or username, and fetch Chess.com games from public monthly archives.
Where are my imported games saved?
On your device. Imported games and finished reports are stored in your browser, so recent games reopen instantly and nothing is uploaded anywhere.
Does the chess engine run on a server?
No. A Cloudflare-compatible lite Stockfish NNUE build runs inside your browser while you analyze. Your games stay on your device and no server performs engine analysis.
How are accuracy and move labels calculated?
Every nonterminal position is evaluated by Stockfish and converted to winning chances. Suspected errors are checked again at a common exact depth before the final report. Inaccuracy, Mistake, Blunder, mate handling, accuracy, and ACPL follow Lichess's current formulas. Great and Brilliant are stricter ChessAnalyser extensions and appear only after deep verification.