Chess Solver

Set up any chess position — or paste a FEN — and a real engine gives you the best move, an evaluation bar, the likely line and any forced mate. Then switch to Play to play the position out, let the engine move, or watch it play itself. Everything runs in your browser, nothing is uploaded.

How to Use the Solver

The board has two modes. In Set up, choose a piece from the palette and click a square to place it — hold and drag to place several, use Erase to clear one, or press Start position, Clear board or Flip board. Set whose turn it is, then press Analyze: the best move lights up with its notation, the bar on the left shows the evaluation, and the likely line is written out below. Castling rights are worked out automatically from where the kings and rooks stand. Switch to Play to play the position out — click a piece then a highlighted square to move, press Engine move to let the engine reply, Run to watch it play both sides, and Undo to take moves back. Pick a Lesson to practise a specific win, or Random game for a fresh position to play every time. You can also paste a position as FEN, or Copy FEN to save one.

How the Solver Works

The engine is a real negamax search with alpha-beta pruning, a quiescence search for tactics and a positional evaluation (material, piece-square tables, king safety, pawn structure and passed pawns). From the position you set up it searches ahead as far as it can in about a second, then reports the move that leads to the best result it can see, the evaluation in pawns from White's point of view, and any forced checkmate as mate-in-N. It's strong club-level analysis — excellent for finding the best move and spotting tactics — but it runs entirely on your device, so it isn't claimed to match a dedicated engine like Stockfish. Nothing you enter leaves your browser.

Frequently Asked Questions

How do I enter a position?
In Set up mode, pick a piece from the palette and click or drag across the squares to build the position you want; the eraser clears a square. Set whose turn it is, then press Analyze — castling rights are detected automatically from where the kings and rooks stand. You can also paste a FEN string and press Load FEN to bring a position across from another board.
Can I play the position out?
Yes — the chess solver doubles as an opponent: switch to Play mode, then click a piece and a highlighted square to move. Press Engine move to let the engine reply, Run to watch it play both sides until you pause, or Undo to take moves back. You can also pick a Lesson to practise a specific win, or Random game for a fresh position to play each time.
What does the evaluation bar mean?
The evaluation bar shows who stands better and by how much, measured in pawns from White's point of view. A value near zero is roughly equal; a large value means a winning advantage. When a forced checkmate is found the bar switches to M followed by the number of moves to mate.
Is this as strong as Stockfish?
No — this chess solver is not built to match Stockfish, but it is a real negamax engine with alpha-beta pruning and a positional evaluation. It returns strong club-level analysis in about a second, which is enough to find the best move and spot most tactics. For deep correspondence-grade analysis a dedicated desktop engine will still go further.
Does it detect checkmate and stalemate?
Yes — the solver detects checkmate and stalemate automatically. If the side to move has no legal moves, it reports checkmate when that king is attacked and stalemate when it is not, and it also flags positions drawn by insufficient material. The position is checked for legality before the search starts.
Is anything uploaded?
No — nothing you enter is uploaded. The board, the FEN and the whole search run in your browser, so no position is ever sent to a server. Closing the tab clears everything you set up.

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Put the Chess Solver on your own page — free, no sign-up, no watermark. It runs entirely in your visitors' browsers. Copy the snippet and paste it into your page's HTML.

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