Chess Analysis Board
Move the pieces, paste a FEN or PGN, and let Stockfish show the best lines for any position.
FEN rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
How to use the online chess engine
- Drag pieces to play moves from the starting position, or paste a FEN or PGN and press Load position.
- Press Analyze with Stockfish. The engine loads once (about 2 MB) and then follows every position you visit.
- Read the three best lines with their evaluation, and step back and forth through your moves with the arrows.
Need to place pieces freely, for example a puzzle or an endgame? Build it in the chess board editor and open it here in one click. To review a whole game, use the free chess game review.
About the engine
Stockfish is the strongest open-source chess engine and is free software under the GPL. This board runs the unmodified Stockfish 19 lite build; its licence and source code are linked on the Stockfish licence page. The lite build uses a smaller neural network so it loads quickly in a browser; it is still far stronger than any human player.
Frequently asked questions
Which Stockfish version does the analysis board use?
Stockfish 19, lite single-threaded build, compiled to WebAssembly. It runs in your browser, so nothing is sent to a server and there is no usage limit.
How do I read the evaluation?
Scores are from White’s point of view in pawns: +1.00 means White is about a pawn better, −2.50 means Black is clearly better. #5 means White mates in five moves; #-3 means Black mates in three.
How deep does the engine search?
Up to depth 20 with the three best lines shown. Depth climbs over a few seconds; on a phone it may take a little longer. The arrow on the board shows the current best move.
Can I analyze a game instead of a position?
Paste a PGN to step through the game and analyze any move, or use the free chess game review to get accuracy and mistakes for the whole game at once.