Privacy
Last updated 16 September 2026
No accounts
There is no login and no account. You can use the calculators without giving us an email.
Analysis stays in this tab
The best-move calculator runs Stockfish 18 as WebAssembly in your browser. A FEN you paste or a position you set on the board is not uploaded to our servers.
Game imports
If you import a Chess.com or Lichess game, we fetch the public PGN from that site so the engine can run here. We do not keep a copy after the response is sent. Private games stay on those sites.
Pathwise explanations
When Pathwise explains a move, your browser sends a small packet of verified facts to our server: the positions (FENs) before and after the move, the two moves being compared, the move's quality grade and evaluation delta, the engine's suggested line, your chosen explanation level, and the opening preset you selected (if any). Our server checks these facts against the positions and forwards them to a language-model API to compose the wording. No username, no game history, and nothing that identifies you is included, and we do not store any of it. If no language-model key is configured, nothing leaves the tab and the explanation is composed on your device.
What this browser stores
If you switch Light or Dark, that choice is saved under the localStorage key tcc-theme. Clearing this site's data removes it.
Analytics
On thechesscalculator.com we load Google Analytics 4 (measurement ID G-ZLPH1X23VE) so we can see which pages people open. That script may set first-party cookies such as _ga. Positions, FENs, and engine analysis are not included in our custom analytics events.
We also use Umami and OpenPanel, both hosted on our own server, to count pageviews, referrers, outbound link clicks, and calculator actions. Neither sets analytics cookies. We exclude URL query strings and fragments from their page tracking so shared board positions are not recorded in analytics.