BlunderbookChess analysis for iPhone
Find the move that lost the game.
Blunderbook pulls in every game you have played on Chess.com or Lichess and runs Stockfish 19 right on your iPhone. See the exact moment a game turned, why it turned, and what you should have played instead.
- Stockfish 19 on device
- Chess.com & Lichess
- No account
Game review
See the moment it turned.
Every move is scored by how far it moved the evaluation bar. Blunderbook takes you straight to the key moments, so you look at the few moves that mattered instead of all forty.
- Key moments, one tap apart. Jump from swing to swing through the game.
- Stockfish’s three best lines for any position, live, under the board.
- Arrows on the board show what you played and what the engine wanted.
Accuracy
Three rings. No excuses.
Every analysed game gets three rings: your accuracy for the game, the last 30 days and the last 12 months. Chess.com and Lichess games are measured the same way, so the numbers mean the same thing wherever you play.
- A grey ring is an open question. Tap it and that game is analysed.
- Watch the trend, not just the last result.
Mistakes · Premium
Your blunders, back as puzzles.
Every inaccuracy and blunder from your in-depth reviews lands in one list. Blunderbook shows the kind of mistake you keep making, then hands each position back to you to find the better move.
- Biggest leak. The pattern costing you the most, in plain words.
- Opening hot spots. The lines where your games go wrong, and around which move.
- Solve them again until the right move comes first.
Explore
Play it out against Stockfish.
Think you had something better? Branch off from any move and play your idea. Stockfish answers with its best reply, so you find out right there whether it would have worked.
How it works
From username to insight.
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Add your username
Chess.com or Lichess. No sign-in, no password. Your whole history comes down.
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Open a game
Stockfish analyses it on your phone, and keeps going while you use other apps.
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See what happened
Key moments, best lines and accuracy, saved on your phone to come back to anytime.
Private by design
Your phone does the thinking.
On device
Stockfish runs on your iPhone. Your games are never uploaded anywhere to be analysed.
No account
Just a public username. Nothing to sign up for, no password to hand over.
Yours to keep
Reviews stay on your phone, and you can export everything to a backup file whenever you like.
Plans
Free to analyse. Premium to improve.
Free
Everything you need to review your games
- Analyse any game you open, as many as you like
- Quick and Standard depth, up to 1.5M nodes a position
- Accuracy rings, key moments and engine lines
- One tracked player, with their whole history
- Saved reviews stay readable, always
Premium
Start with a free trial
- Everything in Free
- Mistakes: your errors, collected and drilled
- Deep and Deepest reviews, 3M and 6M nodes a position
- Track as many players as you like
Monthly, billed through your Apple Account. Cancel anytime in Settings.
Screens
Built for the board.
