Privacy

Last updated: May 22, 2026

Spine is a personal book-ranking app. This page explains what we collect, how we use it, and how to remove it.

What we store

Your account: email address, the username and display name you choose, an optional bio and avatar URL.
Your shelf: books you’ve added, the buckets and positions you assigned, comparisons you ran, your want-to-read list, custom shelves.
Activity: who you follow, ranking events that appear in your followers’ feeds.
Anonymous sessions: a random ID stored in a cookie so unsigned users can build a shelf before they create an account. When you sign in, anonymous data is claimed to your account.

Neon — managed Postgres database. Stores everything above.
Resend — sends sign-in magic-link emails. Receives your email address to deliver the link.
PostHog — product analytics and error tracking. Receives pseudonymous usage events. After sign-in we identify the analytics session with your user ID; we do not send your email or other personal details as event properties.
OpenAI — generates book recommendations on the Discover tab. Receives your bucket lists (titles + authors) to suggest similar reads. Not used for training.
Open Library & Google Books — public APIs we query when you search for a book. They see the search term, nothing about your identity.
Vercel — hosting. Receives standard server logs.

We don’t sell your data.
We don’t serve ads or use third-party advertising trackers.
We don’t share your shelf with anyone except via the public profile URL you control.

Delete your account at any time from Settings. This removes your books, comparisons, shelves, want-to-read, follows, and profile permanently.
Sign out to end the current session.
Public profile visibility is on whenever you pick a username. If you want a profile gone, delete your account.

Questions about this policy? Email hello@cardboard.rip.