How it works
How to analyze your chess games with Audit Chess
Audit Chess turns your real Lichess and Chess.com games into a training plan in three steps. Enter your username, let Stockfish analyze every game in your browser, and get a full review, puzzles from your own blunders, and a ranked list of your weaknesses. It is free, needs no account, and nothing is uploaded - the analysis runs on your device.
- 1
Enter your username
Paste your Lichess or Chess.com username (or upload a PGN file) and pick a colour. There is nothing to install and no account to create - you start in one click.
- 2
Stockfish analyzes in your browser
Audit Chess pulls your public game history and replays every game through Stockfish running locally in a Web Worker on your own device. Nothing is uploaded to a server - the analysis happens on your machine.
- 3
Get your review, puzzles and weaknesses
You get move-by-move game review with accuracy scores, an opening tree, every opening ranked by result, your endgame and playstyle profiles, blown-wins detection, activity analytics and period reports - and puzzles built from your own blunders. Press "Explain game" for plain-English, engine-checked notes on any game, build and drill your own repertoire, or scout an upcoming opponent.
Technical Details
- Engine: Stockfish 18 (lite build), compiled to WebAssembly (WASM)
- Accuracy: A 0–100 score based on how much winning chance each of your moves gave up versus Stockfish's best play, so one big blunder counts for more than several tiny slips.
- Move labels: Each move in a single-game review is graded Brilliant, Great, Book, Best, Excellent, Good, Inaccuracy, Mistake, Miss or Blunder.
- Data sources: Lichess public API, Chess.com published game API
- Privacy: Your games are never uploaded or stored - engine analysis runs entirely in your browser. Only the optional AI features (AI insight cards, help chat) send a short text summary to generate their response; Explain game builds its comments in your browser from engine-verified facts.
Frequently asked questions
How does chess game analysis work?+
Each game is replayed position by position through a chess engine (Stockfish) that evaluates every move. Moves that lose evaluation are flagged as inaccuracies, mistakes or blunders, and the drop across a game becomes an accuracy score. Audit Chess does this for your whole history at once.
Is Audit Chess really free with no account?+
Yes. It is free and requires no account or sign-up. You enter a public username and analysis begins.
Is my chess data uploaded anywhere?+
No. Stockfish runs in your browser, so your games are analyzed on your own device rather than sent to a server.
How many games can it analyze?+
Audit Chess analyzes around 1,000 games in under a minute and scales to about 5,000.