Last updated: July 12, 2026
Your privacy matters. Marble is a local-first ebook reader. It requires no account, uses no analytics SDKs, and keeps your library on your device unless you choose optional sync or cloud import.
Short Version
- We do not collect any personal data on servers we operate.
- We do not use analytics SDKs or third-party trackers.
- We do not require an account or sign-up.
- Your books, highlights, notes, and reading stats stay on your device by default.
- Optional iCloud sync uses Apple's CloudKit; book files are not uploaded.
- Optional Google Drive / Dropbox import uses OAuth you initiate; tokens are stored in the iOS Keychain.
Information We Collect
None on our servers. Marble does not collect, transmit, or store personal information on any server we operate. No analytics, no advertising identifiers, no profile building.
Data Stored on Your Device
Marble stores data locally in its sandboxed container, including:
- Book files you import (EPUB, PDF, TXT, DOCX, CBZ, and related covers)
- Library metadata (titles, authors, tags, series, progress)
- Highlights, notes, and annotation browser state
- Reading statistics (time, pages, streaks, heatmap) when you use that feature
- Typography and theme preferences
- OPDS catalog URLs and Calibre Content Server connection details you add
- Cloud import account tokens (Google Drive / Dropbox) — stored in iOS Keychain
iCloud Sync (Marble Pro, optional)
Marble Pro can sync reading positions and annotations across your iPhone and iPad via Apple's CloudKit. Book files remain on each device. You can turn sync off in Settings. Sync data is not accessible to us.
Cloud Storage Import (optional)
If you connect Google Drive or Dropbox, Marble uses that provider's OAuth flow so you can browse and import books. Credentials and tokens are stored in the iOS Keychain. We do not operate those services and do not receive your cloud passwords. You can disconnect at any time in Settings.
OPDS & Calibre
When you browse OPDS catalogs or a Calibre Content Server, Marble connects directly to servers you choose. We do not operate those servers and do not see your traffic.
Crash Reporting
We do not use third-party crash reporting. If you opt in to share crash reports with Apple via the standard iOS dialog, that data goes to Apple under their privacy policy.
In-App Purchases
Purchases (including Marble Pro) are processed by Apple via the App Store. We do not receive or store payment information. Entitlement is verified on-device via StoreKit.