Chess Fluency
Spaced repetition for chess
See the right move in two seconds, not two minutes. Chess Fluency turns your own mistakes, your openings and the patterns strong players see instantly into positions you play out on a real board, each one scheduled to come back just before you would forget it.
Free and open source. Works on your phone. Connects to Lichess or Chess.com.
Why
As a polyglot and a passionate language learner, I've tried most ways of learning a language. The biggest difference by far came from spaced repetition: seeing each word again at just the right moment, until recalling it takes no effort at all. Vocabulary doesn't stick from one pass through a textbook. This is how it sticks.
Chess works the same way. Its patterns are its vocabulary: a fork, a pin, a back-rank mate are words you either recognize at a glance or have to spell out letter by letter. Openings and typical plans are its grammar and its set phrases. Working out a position you don't recognize is like translating word by word with a dictionary: you can get there, but slowly. Fluent speakers don't translate, and strong players don't calculate everything. They recognize it, because they've met it many times before.
In chess I could solve hard puzzles if I was patient enough, but in bullet and blitz I didn't see the same ideas fast enough. What was missing wasn't calculation. It was recognition. I wondered for a long time when someone would combine spaced repetition with a real chessboard and your own games. Then it occurred to me that I could make it.
It learns from your games
Connect Lichess and Chess Fluency reads your games: every error, the positions where you slip again and again, and the patterns behind them. Then it turns them into cards.
One pass over your recent games and puzzles weighs every error: the ones you repeat, how slow the game was, how much time you had left, how long you thought. Then it builds the few decks worth the most to you, and suggests what to add later, so you never take on too much.
Positions you've misplayed in several games, usually an opening line you meet again and again, come first. Fix one and it pays off every time it comes up.
The position, the move you played, the move you missed, tagged with what went wrong. The most instructive come first: errors that changed the result, not slips in a game you were winning anyway. In correspondence games, every inaccuracy counts.
The moment after the opening when everyone is developed and the plan isn't obvious. Taken from your games, especially where you then went wrong, followed by master games that reached a similar position.
Your missed Lichess puzzles come back on a schedule, once enough time has passed that you have to see the idea again. Easiest or hardest first, to match your focus.
Your blind spots by type of position, the openings where you go wrong most, the tactics you miss and walk into, and the habits behind quiet errors: long thinks that end badly, minor-piece trades that let the tension go, locked centers. Each one has a drill.
How you train
About thirty named mates in the order Lichess Practice teaches them, each with real positions from easy to hard. Know them by sight and you start steering towards them.
Thirty puzzles of one theme, from easy to hard: the tactics your games show you miss, or ones you've never drilled, like zugzwang.
Build a repertoire from the Lichess opening explorer or import any Lichess study. Watch a new line once, then play it from memory; forgot one, watch it again. At the end of any line, see what's played next.
Seventeen classic opening traps, drilled as: dodge it, punish it, and set it. The ones you've fallen for in your own games come first. Every line is checked by Stockfish.
In a puzzle you know there's a shot. In a game you don't. Decide first, then play: a real puzzle or a quiet position, on a coin flip every time.
Every move is timed against your own history on that card. Faster than usual pushes it further out; slower brings it back sooner. Pause any time.
After each card, replay why your move fails and why the best move works, or open the analysis board: Stockfish looks deeper as you watch, with an evaluation bar and the opening explorer.
Everything at once, only what fixes your own errors, only new material, or a single folder or deck. You decide what goes into the mix.
Add it to your phone's Home Screen, iPhone or Android, and study on the train or on a plane: Stockfish runs on your device, and your progress syncs when you're back online.
Stockfish runs right in your browser and accepts any move that is just as good, so a different winning idea still counts. Your progress syncs between your phone and computer through your Lichess login, and decks can be exported to Anki or MintDeck. Every feature, why it's there and how to get the most from it: the guide.
Why spaced repetition
You forget on a curve. Right after you learn something, memory fades fast, then more slowly. Psychologists have measured it since the 1880s.
Recalling beats rereading. Pulling an answer out of memory strengthens it far more than looking at it again. That's why every card asks you to play the move, not just look at it.
Timing is everything. A review just before you would forget does the most good, and each successful one lets the next wait longer: a day, a few days, a week, a month. Your time goes to what you're about to lose, not to what you already know.
I learned this the hard way. I had already studied French, German and Spanish, and found I had both a passion and a knack for languages. Then I moved to Beijing and started on Chinese, and for the first time I wasn't progressing as fast as I'd hoped. I felt I needed to revolutionize how I studied. After a lot of research I found Anki and spaced repetition.
Being consistent with it made a huge difference: my Chinese grew much faster than before. Since then I've believed that timing your reviews well is an essential part of learning anything new efficiently. Chess Fluency is that idea, on a chessboard.
Every position is a card. After you play it, you rate it Again, Hard, Good or Easy, and the app suggests the rating from whether you found the move and how your speed compares with your own past times. The FSRS algorithm, the modern scheduler in Anki, then works out when your recall would drop to about 90% and brings the card back right then.
Open source
Chess Fluency stands on the work of the open source chess world: the Lichess board, rules library, puzzle database and opening explorer, the Stockfish engine, and the FSRS scheduler. It is free, with no ads and no account of its own, and its code is open under the GPL.
Your data. Your cards and progress live in your browser. To sync between devices they are also kept on this site's server, filed under your Lichess username. Your Lichess login itself is never stored there, only a one-way fingerprint of it to recognize you. Nothing is sold or shared. (If you choose to share what made a hard position click for you, I may read it, to explain such positions better.)
Support
If Chess Fluency helps your chess, you can chip in toward the time it takes to build and improve.
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