Call Number Privacy Policy

Last updated 21 June 2026.

Call Number is a personal library catalog. It works on your device without an account; signing in is optional and only enables syncing your library across your devices and sharing it with people you invite. This policy explains what we store when you sign in.

What we collect

• Your Apple account identifier. When you sign in with Apple we receive a stable, app-specific ID, and — only if you choose to share them — your name and email (which may be Apple's private relay address). We key your account on the Apple ID, never on email.
• Your catalog. The books you add (title, author, identifiers, cover reference, description, subjects) and where they're shelved (buildings, rooms, bookcases, shelves).
• Your reading list. Which books you mark "to read." This is private to you and is never shown to other members of a shared library.
• Loan records, if you use them. A borrower's name you enter is third-party information; please only record it with their understanding.

How it's stored and shared

Data is stored in a managed PostgreSQL database (DigitalOcean), encrypted in transit (TLS) and at rest by the provider. If you share a library, the people you invite can see and edit that library's catalog — but never your private reading list. We do not show ads, and we do not sell your data. The only processors involved are Apple (sign-in) and our hosting provider.

Deleting your account

You can delete your account from the app. Deletion revokes the Apple sign-in link, deletes your sessions and your private reading-list data, and either transfers your shared libraries to another member or removes them. Note that routine encrypted backups may retain data for a limited retention window before they expire.

Contact

Questions about your data: [email protected] (Creative Sonar, LLC).