Stockfish reads every position.
Stockfish 18 checks each move of your completed games. On Free it runs in your browser; on Pro our server analyzes them, so they are usually ready before you open the app.
Example review
This is what one moment looks like
An invented position, not anyone’s game. Blunderbase finds moments like this in your own completed Chess.com and Lichess games, shows what the move cost, and turns it into practice.
The game so far
- 1.e4 e5
- 2.Nf3 Nc6
- 3.Bb5 a6
- 4.d3??
Stockfish checks every move. Most are fine; this one is flagged.
The move that was playedWhat the engine plays instead
Blunder Missing an opponent threat
- Game move
- d3??
- Best move
- Ba4
- Evaluation loss
- 4.56 pawns
Why d3 fell short
Your opponent could win material by capturing your bishop on b5, and your move did not resolve that threat. Stockfish plays Ba4 Nf6 O-O.
Next time First ask what your opponent is threatening.
In the app, from here
- Try from move 4Set the board back to before d3 and play your own idea.
- Play Ba4Step through the engine’s line one move at a time.
- Practice this positionSend it straight to your personal puzzles.
How this move was judged
Nothing on a review is a guess. Each label has a rule behind it.
53% to 17%.
d3 took White’s winning chances from 53% to 17%. Severity follows that drop, so a pawn lost in a game already won counts for less than one lost in a level game.
Only what the board proves.
The pattern is named only when the position shows it: a6 attacked the bishop, and d3 left it there. When nothing proves a pattern, the review says so instead of guessing.
Then it becomes practice
The position joins your personal puzzles, starting from the board above. Each first-try solve sends it further out; a miss sends it back to the start, the next day. After the last gap it counts as learned and leaves your queue.
- TodayFound in review
- 1 dayAfter a solve
- 3 daysAfter a solve
- 7 daysAfter a solve
- 14 daysAfter a solve
- 30 daysAfter a solve
- LearnedLeaves the queue
One moment is one part of a review
Every game you import gets the same treatment, and the patterns add up.
The game’s story.
How the game ended, the turning point, and up to three lessons picked from the flagged moves.
Accuracy, opening, clock.
Accuracy for every game, your record in the opening you played, and the time spent and left at the turning point.
Insights across games.
The patterns that keep coming back in your recent games. Free shows the top three.
Ask the coach.
From any lesson or finished puzzle, ask why a move failed and get the reason in plain words.
A weekly program.
One weakness from your own games, three short sessions, and a check against the games you play next.
Reviews that come to you.
Imports every half hour, a review email after each session, and a monthly report.
Your games have moments like this.
Every new account starts with seven days of Pro. No card, and nothing to cancel: after the week you are on Free unless you choose Pro.