Free Chess Analysis Board
Paste a game and step through it with the engine running.
How to use it
- Paste a game into the box. A PGN, a single FEN, or a lichess game link all work, and the page tells you which one it recognised before you load it.
- Press Load it. The moves appear beside the board.
- Use Back and Forward to walk the game, or tap any move in the list to jump straight to it.
- Press Turn the engine on when you want evaluations. The engine downloads once, roughly 7 MB, and is cached afterwards.
Chess.com does not let a page read a game from its link, so paste the PGN instead: open the game, press Share, copy the PGN, paste it here. Lichess links load directly.
Reading the evaluation
The number beside the board is in pawns and always from White's point of view. +1.0 means White is a pawn up in effect, -2.5 means Black is winning, and #3 means mate in three. The bar next to it is the same number drawn as a picture, so a glance is enough once you are used to it.
The number moves as the search gets deeper, which is normal and worth watching. An evaluation that jumps around means the position is sharp and the engine is still resolving it. One that settles immediately means the position is quiet, and your move choice there matters less than you think.
What actually tells you something is the change between two consecutive positions. A quiet game is a flat line. A game decided by one mistake is a flat line with a cliff in it, and the move at the top of that cliff is the only one worth studying.
Trying your own move
Stop anywhere and play a move on the board. It becomes a branch: the original game is still there, indented alongside your line, and Back walks you out of the branch the same way you walked in. That is the whole reason to use an analysis board instead of just reading a game review. Reviews tell you what happened; a board lets you ask what would have happened.
Use it on the moves you were unsure about while you were playing, not on the ones the engine calls mistakes. Those are different sets, and the first one is where your actual understanding is.
If you want to build a position rather than reach it, the board editor places pieces by hand and hands the result back to this page.
What an analysis board will not tell you
An engine answers one position at a time. It has no idea that you have hung a piece to the same knight fork in eleven of your last twenty games, because it never sees the twenty. That is not a limitation of this page, it is what an engine is.
The gap between one position and a pattern is the whole gap between analysis and improvement. Chess DNA reads your last 25 games from Chess.com or Lichess, runs the same engine over every move, and sorts what it finds into nine weakness themes, so the thing that keeps costing you rating shows up as a theme instead of as twenty separate bad afternoons.
If you only want one game graded rather than explored, the free game review gives accuracy, move classifications and the moves that decided it.
Frequently Asked Questions
What is a chess analysis board?
A board you can move pieces on with an engine evaluating alongside, used to replay a game and test alternatives. This one loads a PGN, a FEN or a lichess link, lets you step through the moves, and branches whenever you play something different.
Is this analysis board free?
Yes. Stockfish runs in your own browser, so there is no server cost to pass on and no reason to charge or ask for an account. There is no limit on how many games you analyse.
Can I analyse a Chess.com game here?
Yes, but paste the PGN rather than the link. Chess.com does not let another page read a game by its URL. Open the game, press Share, copy the PGN and paste it into the box. Lichess game links load directly.
Does my game get uploaded anywhere?
No. The engine is WebAssembly running on your own device, and the game you paste never leaves the browser tab. The only download is the engine itself, about 7 MB, and only when you turn it on.
Can I get back to the game after trying my own move?
Yes. Your move becomes a branch shown alongside the original line, and pressing Back walks you out of it. The game itself is never overwritten.
