Privacy
Last updated 9 November 2026.
Positions and games
The move calculator, board editor and analysis board all work in your browser. Stockfish runs on your device in a separate worker. The positions and PGN games you enter are not sent to us or to anyone else.
As you change the position, the page's address updates to include it after a # (as #fen=…), so you can bookmark or share it. Browsers never send the part after # to a web server, so the position does not reach our server or its logs, even when you reload or open a shared link. Anyone you share the link with can see the position.
Visits
Page views are counted with Umami, an open-source analytics tool we host ourselves. It records the page, the referring site, browser, device type and country. It sets no cookies and does not store your IP address. It is set not to record the parts of the address after "?" or "#", so positions are not recorded.
We also count a few actions as anonymous events, to learn which features are used: finding a best move (with the search depth), loading the engine (with how long it took), loading a PGN (with the number of moves), copying a FEN, and analysing a game (with the number of moves). The events never include the position or the game.
Stored on your device
If you pick light or dark mode with the switch in the header, your browser remembers that choice (in local storage) on this device only. Your browser also caches the engine file so it does not download again.
Hosting
The site is hosted by Hostinger, whose servers keep standard access logs (IP address, time, page requested) for security and running the service. Fonts and the engine are served from this site, not from a third party.