Free chess analysis board with Stockfish
Set up any position, paste a FEN or a PGN, and explore variations with Stockfish 18 evaluating as you go. No sign-up, no limits, and the engine runs in your browser rather than on our servers.
Engine
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Engine starting in your browser…
Three ways to load a position
Drag the pieces from the starting position, paste a FEN to jump straight to a specific position, or paste a full PGN to pick up where a game finished. Copy FEN hands the current position back so you can save it or share it somewhere else.
Every move you play from there becomes your own variation. Back steps out of it one move at a time, and Reset returns the board to the starting position. There is no separate “analysis mode” to enter — the engine is always watching the position on the board.
Reading the evaluation honestly
The bar and the number are centipawns from White’s point of view. Positive favours White, negative favours Black, and a mate score takes over when a forced mate is on the board. What the number does not tell you is how hard the position is for a human to play, and that gap is where most club-level games are actually decided.
The depth readout is there for the same reason. Engine evaluations are provisional until the search settles; a tool that shows you a confident number without telling you how far it looked is hiding the one thing you need to judge it. Watch a tactical position climb through the depths and you will see the number move a long way.
Analysing a position rather than collecting evaluations
The most common way to waste time with an analysis board is to click through a game watching numbers go by. Nothing sticks, because you never committed to anything the engine could correct.
A better loop takes about a minute per position. Decide what you would play and why. Play it on the board. If the evaluation holds, you were right for a reason you can now name. If it drops, step back and find the move you missed — and try to state what you failed to look at, not just which move was better. That sentence is the part that transfers to your next game.
When the board explains a move — and when it says nothing
Where a named principle genuinely applies, the panel names it: material hanging, a threat that needs meeting, a square worth occupying. That text comes from a deterministic rule engine reading the board directly, not from a language model producing plausible chess prose, and the engine keeps a veto over anything the rules want to say.
Most of the time it stays silent. On our own measurement corpus the principle layer declines to speak in roughly seven positions out of ten, because most positions are not about a principle — they are about a concrete line. We would rather show you nothing than dress up an engine move in a rule that was not really doing the work.
Frequently asked questions
- Is this chess analysis board free?
- Yes. There is no account, no daily analysis limit, and no paid tier that unlocks more depth. The engine runs on your machine rather than ours, so there is no per-position cost to pass on.
- Do I need an account to use it?
- No. The board works immediately. An account only matters if you later want your own games synced across devices, which is a separate part of the site.
- Can I paste a PGN as well as a FEN?
- Yes. Paste either into the box and press Load. A FEN loads that exact position; a PGN loads the final position of the game, which you can then step back from by exploring your own moves.
- Which engine does it use?
- Stockfish 18, compiled to WebAssembly and running in a web worker in your browser. The page shows the depth it has reached so you can tell a settled evaluation from an early one.
- Does it work offline?
- Once the page and the engine have loaded, analysis keeps working without a connection, because nothing is being sent anywhere to be evaluated.
- How is this different from the analysis board on Chess.com or Lichess?
- For raw engine output it is not very different, and both of those are excellent. The differences here are that the search depth is shown rather than implied, and that when a named chess principle genuinely applies to the position the board will say which one — and stay quiet when none does.
A board tells you about one position. If you want to know which mistake is costing you the most rating across many games, that is a different question — and it is the one the rest of this site answers.
Analyze your games free