Legal
Privacy
Last updated 14 August 2026. Hard Lines is operated by Louis Verstraeten (Belgium).
What this product stores
Hard Lines is local-first. Your PGN files, catalog order, and spaced-repetition progress live in IndexedDB in your browser until you sign in or export a backup.
Optional account
If you create an account (email, magic link, or Google), we store your email with Supabase Auth (hosted in the EU) and sync your library and progress to your account so you can use another device. You can keep using the trainer without an account.
Game check
If you look up recent chess.com games, we send the public username you typed to chess.com through our server. We do not store that username on our servers.
Analytics and errors
The site may use Vercel Web Analytics for page-view counts. That product is designed not to use advertising cookies. If Sentry is enabled on the deployment, anonymous error reports may be sent so crashes can be fixed. Do not put secrets in PGN comments you would not want in a backup or error trace.
Your rights
You can export a JSON backup from Settings, delete individual repertoires, reset progress, or delete your account (which removes the cloud copy and the login). To ask for a copy or deletion of account data, use the contact page or email louisverstraeten2002@gmail.com.
Processors
Hosting: Vercel. Auth and synced library: Supabase. Optional sign-in: Google, if you choose Continue with Google. Optional game lookup: chess.com's public API.