Privacy

BookNook works without an account. Until you sign in, your library stays on your phone.

If you sign in to sync

What is stored: your email address (or your Google account's email and id), and your library: books, shelves, ratings, notes, photos you took for covers, and your app settings (theme, shelf order).
Where: a Supabase project hosted in the EU (Frankfurt). Each account can only read its own rows; this is enforced by the database (row level security), not just the app.
What is not collected: no analytics, no advertising ids, no tracking, no contacts or location. The camera is used only to read barcodes and take cover photos, on the phone.
Who else sees it: nobody. Supabase processes the data on BookNook's behalf. Searches, barcode lookups and cover images go to Open Library, which sees the search, not who you are.

BookNook is bought through Google Play. Google handles the payment; the app never sees your payment details.

Sign out (Settings → Account & sync): the phone stops syncing and keeps its copy.
Delete account (same place): deletes the account, every synced book, note, setting and cover photo from the server immediately. The copy on your phone stays until you uninstall the app. No longer have the app? See Delete your account.
Phone backups to Google are switched off; the in-app export is the only other copy.