Chessility FAQ
The short version of how this chess trainer works — ladder, best moves, threats, and Rush.
What is Chessility?
Chessility is a free chess trainer in the browser. You play Stockfish bots, see the engine’s best move, and get a threat highlight when something of yours is hanging. There are no accounts — progress stays on your device.
How does the opponent ladder work?
Start with Plankton (~400). Win 3 games against a bot to unlock the next one, up to The Auditor (~2200). Beaten bots turn green on the opponents page.
What does “best move” mean?
The best move is Stockfish’s top choice in the current position after it thinks. Matching it raises your accuracy. Excellent near-best moves count as half a best move. Hints show the engine arrow when you are stuck.
How is accuracy scored?
Accuracy is (best moves + half of excellent moves) divided by your moves, as a percent. It is stored locally with your best win against each bot.
How does Best Move Rush work?
You get 60 seconds of positions in a row. Play the engine move to score a point and keep the streak. A miss resets the streak and costs a short pause — the clock keeps running. Mate-in-one positions accept any mating move.
What does “spot the threat” mean?
After the bot moves, Chessility can highlight a hanging piece, a winning capture, or a check you must answer. The red cue is the engine’s next punch if you ignore it. See the threat guide for how to train that habit.
Do I need an account?
No. Wins, unlocks, rush scores, and a short game history stay in your browser. Clearing site data resets progress. Optional feedback can include an email only if you type one.
Next: how to spot the engine’s threat, meet the Stockfish bots, or choose an opponent.