Privacy
Private, Offline Chess
LibreChess is built so your chess stays yours. There is no account, no ads and no game upload: the engine and your chess data live in your own browser. Cookieless aggregate traffic and page-engagement analytics are disclosed clearly rather than hidden behind an absolute privacy claim.
On this page
What “private” actually means here
- No sign-up and no email — open the site and play.
- Stockfish receives positions inside a Web Worker in your browser; LibreChess has no remote analysis endpoint. Current position-sharing links keep the FEN in a URL fragment, which is not sent in the page request.
- Current and archived games, local ratings, streaks, repertoire, training progress and settings use browser storage. A game handed from Play, Archive or the PGN viewer to Review can sit briefly in one-use session storage.
- Even the “My Mistakes” trainer analyses your games on your device — they are never uploaded.
What works offline
LibreChess is an installable web app (PWA). A service worker caches the core interactive app after a successful install. Stockfish files are excluded from that initial cache: an engine feature must request them successfully after the service worker controls the page before they are available offline. Once the install and those controlled requests have completed, the interactive play, puzzle, drill, repertoire, archive and review routes can work offline in that browser while its site data remains intact. This is a cache, not a permanent installation guarantee: private browsing, browser eviction, a failed download or cleared site data can remove it. The static field guide is not fully precached, and merely visiting an article does not guarantee that it will reopen offline.
What does leave the device?
Like any website, LibreChess receives the requests needed to send you its pages and files. It also uses Plausible to measure aggregate visits and page engagement without analytics cookies or a persistent cross-day identifier. Those events do not contain board positions, moves, PGNs, FENs, game results, local ratings, repertoire lines or puzzle answers. The exact distinction is documented on the privacy page.
Free to use
The current site has no paywall, account tier or server-side analysis quota. You can export finished games as PGN and saved repertoire lines as JSON, so the useful records are not trapped in the browser. LibreChess also documents how the engine, grading and local storage work. These are present product facts, not a promise that browsers, hosting or the service can never change.