Privacy Policy

Last updated 25 May 2026

Beta note: while OpenBook is in beta, we record error traces and short session replays (only triggered by errors) via Sentry so we can fix bugs. Form-field text is masked by default in those replays. See "Third parties" below.

OpenBook is a chess opening trainer. This page explains what we collect, what we don't, and what we do with it. We've tried to keep it plain.

What we collect

Your Lichess username, returned by Lichess when you sign in.
A Lichess access token, used by our server to call the Lichess Opening Explorer on your behalf. Stored in our database.
Your repertoire — the positions, moves, and notes you save.
Your practice progress (spaced-repetition state).
Your rating band preference.
A session cookie (opaque ID, 30-day expiry) so you stay logged in.

What we don't collect

Email address. We don't request it from Lichess.
Your real name.
Payment information. The app is free.
Analytics, advertising IDs, or cross-site tracking cookies.

During beta we do collect error traces and error-triggered session replays via Sentry — see "Third parties" below.

Cookies

session — opaque ID, HttpOnly, Secure, SameSite=Lax, 30-day expiry. Lets you stay signed in.
lichess_oauth — short-lived (10 minutes), used only during the sign-in flow.

Third parties

Lichess — OAuth identity provider and opening-data source. Their privacy policy applies to the Lichess side.
Neon — Postgres database host (US region). Your repertoire and progress live here.
Vercel — application host. Standard server access logs may apply.
Sentry — error tracking and (during beta) session replay limited to error-triggered sessions. We use this to diagnose crashes. Form-field text is masked by default. Sentry's privacy policy.

Your rights

Export all your data anytime: menu → Export → JSON (a complete backup, including practice progress). A PGN export of your opening lines is also available there for use in other apps.
Delete your account anytime: menu → Delete account. This permanently removes your repertoire, practice state, and any other data tied to your account.
Questions: email feedback@openbookchess.com.

Children

OpenBook isn't directed at users under 13.

Changes

If we change anything material, we'll update the date at the top of this page.