AI Chess Coach
Play Stockfish while every move you make is graded live.
White to move
Stockfish
5:00
You
5:00
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Play Stockfish while every move you make is graded live.
You do not have enough credits to ask the AI.
Ask AI answers your own question about the position in front of you. It sees the board and the engine's best lines, so it can talk about plans, threats and what a move would really cost you - in plain words, not just a number.
For exampleShould I castle kingside next?
The game ends here and goes down as a loss. You can still run the review afterwards, or start a fresh game.
Takes effect from the engine’s next move. The coach is unaffected — it always reviews at full strength.
Coaching mode runs two chess engines at once. The first is your opponent — Stockfish set to whatever difficulty you choose, from a beginner-friendly bot up to full strength. The second is your coach: a separate Stockfish instance pinned to Skill Level 20, the maximum, which never plays a move and exists only to judge yours.
The moment you release a piece, the coach analyses the position twice: once as it stood before your move to find the strongest continuation that was available to you, and once after your move to see where you actually landed. The difference between those two evaluations, measured in centipawns (hundredths of a pawn), is what your move cost you.
Anything from an inaccuracy upwards stops the game rather than just labelling it: the opponent waits while you decide whether to take the move back and try again, or play on from the damage. See Take It Back, Or Play On? below.
Losing evaluation is only half the story. The coach also inspects the move you could have played and works out what kind of chance it was: a forced mate, a piece hanging on an undefended square, a fork, a winning capture, or a promotion. When that opportunity was clearly better than what you chose, a cyan arrow is drawn on the board from the square the piece was on to the square it should have gone to. That arrow is the most useful thing on the page — the tactics you keep missing are the tactics you have not yet trained your eye to see.
When a move costs you something, the opponent does not reply straight away. The board freezes on the error — red square, arrows and all — and you are asked whether you want the move back. Two arrows are drawn: the move you should have played, and the reply Stockfish had ready against the one you chose. Choose Take It Back and the move is undone so you can find something better; the error is struck from your record and the replacement move is graded in its place. Choose Play On and Stockfish answers as normal.
Both answers are useful. Taking it back turns the game into a tactics drill: you know something was there, and now you have to find it. Playing on is the harder discipline — defending a position you have just damaged is the skill that decides most games between club players, and you cannot practise it if you undo every error. A reasonable habit is to take back tactical misses and play on through positional ones.
By default you are offered the move back on inaccuracies as well as mistakes — every move that cost you something. If that interrupts too often, narrow it to mistakes only, or switch it off entirely, under Offer Take Back in the coach settings.
Accuracy summarises the whole game in a single number. It starts at 100 and falls as your average centipawn loss rises — a game where you rarely drop more than a fraction of a pawn per move will sit in the nineties, while a game with two or three serious mistakes lands well below that. It is calculated only on your moves, so beating a weak opponent does not inflate it.
A human coach builds you an opening repertoire, sets long-term goals and holds you accountable — an engine does none of that. What an AI chess coach does better is the part most improving players actually need: instant, objective feedback on every single move, in every game you play. Below about 1800, the fastest rating gains come from eliminating blunders and spotting simple tactics, and that is precisely what a chess blunder checker trains — every blunder flagged the moment you make it, while the position is still on the board. Many players use both: engine coaching for daily play, a human coach for occasional deeper lessons.
Anyone from a complete beginner to a club player around 2000. Beginners should set the opponent to difficulty 1–3 and treat every red square as the lesson; intermediate players get the most from the missed-tactic arrows; stronger players can face full strength and use the accuracy score to measure consistency. It is a chess coach app that runs in your browser — nothing to install — so it is there for every game you play, not just the ones you remember to review.
Every move is graded in your browser — no upload, and no waiting for a server to analyse the game afterwards. The feedback arrives while the position is still fresh in your head, which is exactly when it is worth the most. The one exception is Ask AI, and only when you use it: your question, the position and your last few moves are sent to our server and on to an AI service, which writes the answer.
Already played the game elsewhere? Analyze a finished game instead: enter your Chess.com or Lichess username, or paste the PGN, and the same full-strength engine grades every move of it, scores both players for accuracy and turns your mistakes into practice positions.
Prefer an uninterrupted game? Play Stockfish online without the coach, at any difficulty.