Privacy Policy

Sanjay Gangwar ("we", "us", "the developer") built mBooks as a free application for reading PDF and EPUB books and highlighting passages. This privacy policy explains how the app handles your data.

The short version: Your book files stay on your device — we never upload them. mBooks is completely free with no ads and no subscriptions, and includes no analytics or tracking SDKs. The only data that leaves your device is your highlights, and only if you choose to sign in to sync them across your devices.

Data Stored on Your Device

The following data is stored locally on your device. If you never sign in, this is the only data the app keeps, and it is deleted when you uninstall the app.

• Imported books — the PDF and EPUB files you import are copied into the app's private storage. They never leave your device.
• Highlights — the passages you highlight, their color, position, and any notes you add.
• App settings — such as your default highlight color and theme.

Data We Collect (Only If You Sign In)

Signing in is optional and is used solely to keep your highlights safe and synced across your devices. If you choose to sign in, we collect and store on our servers:

• Account identifier — your user ID and email address from your Google or Apple sign-in, used only to associate your highlights with your account.
• Your highlights — the highlighted text snippets, color, note, in-book position, and a non-reversible content fingerprint (hash) of the book the highlight belongs to. The book itself is never uploaded; the fingerprint only lets the app re-apply your highlights when you open the same book again.

We do not collect analytics, advertising identifiers, location, contacts, or any other personal data. We do not sell or share your data with third parties, and we do not use it for advertising.

How Highlight Sync Works

When you are signed in, highlights you create are stored locally first and then synced to your account so they are available on your other devices and after you sign out and back in. When you sign out, your synced highlights are removed from the device and re-downloaded the next time you sign in.

Permissions and Why We Need Them

• Files / Documents — Used so you can pick a PDF or EPUB to import. The app reads only the file you explicitly choose.
• Photo Library (iOS) — Requested only if you choose to import a book or document from your Photos. The app accesses only the item you select. This permission exists because the file-picker component references the system photo API; if you never import from Photos, it is never used.
• Internet — Used only to sign you in and sync your highlights when you are signed in. With no account, the app works fully offline.

Third-Party Services

mBooks uses Google Firebase Authentication (and Google / Apple Sign-In) to let you sign in. When you sign in, these providers process your sign-in credentials under their own privacy policies. We do not include any advertising, analytics, or tracking SDKs.

Account Deletion

You can delete your account and all synced highlights at any time from within the app (Settings → Delete account). This permanently removes your highlights from our servers and deletes your sign-in account. Uninstalling the app removes all local data from your device.

Data Retention

Synced highlights are retained for as long as your account exists. When you delete your account (or individual highlights), the corresponding data is removed from our servers.

Children's Privacy

mBooks is not directed at children under 13 and does not knowingly collect personal data from them. If you believe a child has provided us data, contact us and we will delete it.

Data Security

Sign-in is handled by Firebase Authentication. Synced highlights are transmitted over encrypted connections (HTTPS) and are scoped to your account so they are accessible only to you. Local data is protected by the operating system's app sandboxing.

Changes to This Policy

We may update this policy when features change. Any changes will be posted on this page with an updated "Last Updated" date. Continued use of the app after changes constitutes acceptance of the updated policy.

Contact

For questions or concerns about this privacy policy, contact:

Trei
Email: contact@trei.dev
Phone: +91 85500 77767
Website: trei.dev  ·  Contact form