About stockfish.io
stockfish.io is an independent chess interface powered by the open-source Stockfish engine. It is not the official Stockfish project and is not affiliated with the Stockfish developers.
Engine: Stockfish 19 / Stockfish.js. See source & licence information.
Local chess analysis
The engine runs on your device. Positions and imported PGN files are processed locally; they are not sent to a chess-analysis server. There is no account or cloud game storage. Export your PGN before reloading or leaving the page if you want to keep a game.
PGN and position editing
One game and its main line are supported per PGN import. Supported headers and the result are retained; comments, annotations and variations are omitted. This is not a lossless PGN editor. Export includes the full current line, even when you are viewing an earlier move.
The position editor checks kings, pawns, material, basic promotion feasibility, checks, castling rights and en passant metadata before analysing. These checks do not prove that every accepted position is historically reachable. Cancel restores the original game and history position; applying a changed arrangement starts a new line after confirmation.
Privacy and advertising
The site includes Google AdSense (publisher ca-pub-6469944033866162). Google's scripts make network requests and may use cookies or similar technologies according to their settings and applicable consent choices. This is separate from the local chess engine. See Google's advertising privacy information. Standard hosting access logs may also record requests.
The analysis workspace is reserved for chess controls. Advertising settings and any required consent messages are managed by the site operator in AdSense. No ad approval or serving status is implied.