Calibre.online and the Calibre 2 mobile apps ยท Last updated 31 August 2026
Calibre.online is an ebook manager and reader. By default it runs entirely on your device: books you add are stored locally in your browser (or in the app's local storage) and are never uploaded unless you create an account.
Your books, metadata and reading progress stay on your device. We do not receive them.
If you sign up, we store your email address, a salted password hash, and the books you choose to sync (files and metadata) so your library follows you across devices. Book files are kept in private object storage and are only accessible to you and to people you explicitly share with. We send transactional emails only (account confirmation, share notifications) via our email provider, Brevo.
We use PostHog to understand how the app is used: page views, feature usage, errors, and a replay of the interface during your visit (clicks, navigation, scrolling). Text you type and the content of the books you read are masked on your device before anything is sent, and are never recorded.
These requests are sent to calibre.online and forwarded by us to PostHog's European servers, so your analytics data is processed in the EU and never reaches a third-party address directly from your browser. It is never used for advertising and never sold. To have your analytics and replay data deleted, email us at the address below.
Open Account in the app and choose Delete account. This permanently removes your account, synced books, libraries and shares. Local data can be cleared by removing the app or clearing site data in your browser.
Calibre.online is built and operated by the calibre.online team, a small independent group of developers. We run the site, the sync service and the mobile apps, and we are the data controller for the account data described above.
This project is not affiliated with, endorsed by, or connected to calibre or its author Kovid Goyal. calibre is a separate desktop application; calibre.online is an independent web project made in its spirit. If you are looking for the desktop calibre, it lives at calibre-ebook.com.
Questions or requests about your data: admin@calibre.online. See also Support.