The whole position, annotated.
Most tools hand you one "best move" and leave the rest unexplained. StockFishy rates every option on the board, piece by piece.
Every legal move, rated
Click a piece and all of its moves light up at once, each on a six-step scale from Best to Blunder, the vocabulary Chess.com and Lichess already use.
A board-wide overview
Before you click anything, every movable piece gets a quiet ring and its own badge, and the three strongest moves are drawn as arrows.
A preview of the reply
A dashed arrow shows what Stockfish expects your opponent to play after the top move. A look ahead, not just a single ply.
Continuous analysis
Switch it on and the position re-analyzes after every move, yours and your opponent's, with nothing left to click.
Runs on your machine
Stockfish is compiled to WebAssembly and runs inside your browser. No position, move or game is ever sent to a server.
One keystroke
Alt+A (Option+A on Mac) analyzes the position without reaching for the mouse.
Six shades of judgment.
Every move is graded against the best one available, so a glance at the color tells you as much as the number.
+1.2 is a modest edge, +4.0 is close to winning. M3 is a forced mate in three; M-3 means walking into one.A training room, built from your games.
The extension is where it starts. Your account turns every game you play into something to learn from.
Every game, graded
Accuracy, an eval graph and move-by-move classifications for each game you play or import from Chess.com and Lichess.
Your blunders, back as puzzles
Spaced-repetition drills built from the positions you actually got wrong, with the move you played and what was better.
15,000 tactics
Rated puzzles, a daily streak and a three-strike Rush mode.
Drill the theory
Practice the main lines of the classical openings until they stick.
Where you lose rating
Opening, middlegame or endgame: see which phase costs you most.
Ready in under a minute.
Add to Chrome
Install from the Chrome Web Store. Works in Microsoft Edge too.
Sign in once
Click the toolbar icon and sign in with Google. Free, no card needed.
Click any piece
Open a game on Chess.com or Lichess and every move gets rated.
Real Stockfish, not a clone.
The official open-source engine top players rely on, compiled to WebAssembly. No proprietary model, no watered-down "chess AI".
Stockfish 18
Default- NNUE evaluation: a neural network trained on billions of positions judges who's better.
- Roughly 46 Elo stronger than Stockfish 17 in engine-vs-engine testing.
- A lightweight build, so analysis loads and runs instantly.
Stockfish 19
Deep Analysis- New SFNNv16 network: drops redundant threat features and adds pawn-structure features.
- One unified network for steadier judgment in sharp, complex positions.
- Trained with quantization-aware training across hundreds of billions of positions.
Free to start.
50 positions a day.
Need more? Upgrade any time for a higher daily limit, and cancel whenever you want.