Opening book
How the opening book knows what your opponents play
Every move played from the position in front of you, how often it is played, and how it scores. It is the difference between preparing a line because a book recommended it and preparing a line because you will actually face it.
Free Included in the free version, with no repertoire or move limit.
How it works
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Pick which games count
The book draws on either the Lichess database of online games or a Masters database of over-the-board games between titled players. They describe two different worlds and it is worth knowing which one you are looking at.
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Set the rating band
With the Lichess source you choose a band: 400, 1000, 1200, 1400, 1600, 1800, 2000, 2200 or 2500. This is the setting that matters most and the one most people leave alone.
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Read the split, and the sample size
Each move shows a win, draw and loss bar with the number of games behind it. A move played four times with a great score is noise, and the game count is what tells you so.
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The same settings drive the scans
The Blind Spot Finder uses this source and rating band too, so what the book calls common is what the finder calls a gap.
Under the hood The exact settings and constants. Not needed to use it.
- Sources
- Lichess games or Masters games
- Rating bands
- 400, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2500
- Shown per move
- Win, draw, loss and game count
- Also drives
- Blind Spot Finder and Smart Trim
- Connection
- Required
- Price
- Free
Those nine bands are worth taking seriously. Which openings appear at all changes enormously across them, and preparing against the wrong band is how people end up studying lines they will never see.
What it will not do
- It reports what happened, not what is correct. A popular move with a good score can still be objectively worse than a rare one, which is what the engine is for.
- It needs a connection. Building and training work offline, but the book does not.
- Online game databases include a great many fast games, so the figures reflect what people play under time pressure as much as what they think is best.
Try it on your own openings
Free to start, with no repertoire or move limit.
No account needed no repertoire or move limit · premium optional