Privacy Policy
Particle is an ebook reader with a synced library, operated by an individual developer. This policy describes what data the Particle apps (iOS, Android, and the web library at particle-reader.com) and the Particle sync service collect, why, and what happens to it.
What Particle collects
- Account. An email address and a password, used only to sign you in. Authentication is handled by Supabase Auth; Particle's own servers never receive your password.
- Your library. The books you upload (EPUB, PDF and CBZ comic files), their cover images, and book metadata such as title, author, identifier, and the original file name.
- Your reading data. Bookshelves, bookmarks, highlights and notes, reading positions and progress, per-book reading preferences, and your in-book search history. These are synced so you can pick up where you left off on another device.
- Subscription. If you subscribe to Particle Sync, the purchase is made through Apple's App Store or Google Play; Particle never sees your payment details. RevenueCat, the subscription service Particle uses, receives the store's purchase record (product, purchase and renewal dates, renewal status, the store's transaction identifiers) together with your Particle account id, so your subscription is recognized on every device you sign in on. Particle keeps the resulting status (active or not, renewal date, which store) with your account.
- Device information. A per-device identifier, device name, platform, app version, and change timestamps, used to keep your devices in sync.
- Server logs and error monitoring. Standard technical logs (such as IP address, requested URL, and timestamps) are generated when you use the service, and server-side errors are recorded with technical details: the failing endpoint and the error, never request contents, your identity, or your IP address. Both are used only to operate and debug the service.
Crash reports (optional, off by default)
If you turn on Share crash reports in settings, a technical report is sent when Particle crashes: what went wrong in the code, plus device model, operating system, and app version. Reports never include your books, notes, reading activity, account details, or IP address. Identifying details are removed on your device before anything is sent.
- Reports carry a random report ID (shown in settings) so you can link a support request to your own reports. It is not connected to your account and is deleted when you turn reporting off.
- Reports are processed on Particle's behalf by Sentry (Functional Software, Inc.) on servers in Frankfurt, Germany, and deleted after 30 days.
- Legal basis: your consent, which you can withdraw at any time by turning the toggle off. The app works identically either way.
Plugins and connected AI apps
The calibre and KOReader plugins sign in with an API key that you create in the web app. They exchange books, book details and reading data with your library and send nothing anywhere else. Revoke a key in the web app to end a plugin’s access.
With MCP you can connect an AI app such as Claude or ChatGPT to your library. Particle asks you to approve each app before it connects. A connected app can read and change book details, shelves and tags, and read your highlights, notes and reading statistics. It cannot open the book files. Whatever the app reads is then handled by the company behind that app, under its own privacy policy. Particle sends nothing to an AI app you have not connected, and keeps a record of each connection: the app’s name, when you approved it and when it was last used. Revoke a connection in the web app under Settings → MCP connections.
What Particle does not do
- No analytics or tracking SDKs. The only diagnostic tool is the opt-in crash reporting described above.
- No advertising.
- No sale or sharing of your data with third parties for their own purposes.
Where your data lives
Particle uses five infrastructure providers, which process data on Particle's behalf to provide the service:
- Supabase — authentication and database for your account and synced library.
- Cloudflare R2 — file storage for your books and covers, stored only in the EU.
- Fly.io — hosting for the Particle application and sync service.
- RevenueCat — subscription status for Particle Sync: the app stores' purchase records, linked to your account id.
- Sentry — server error monitoring and opt-in crash reports, on servers in the EU (Frankfurt, Germany).
All traffic between your devices and these services uses HTTPS.
Retention and deletion
Your data is kept for as long as your account exists. Deleting your account, which you can do under Menu → Account, removes your account, all synced data and your subscription record at RevenueCat. Uploaded files are removed from storage in the same step. If that step fails, the files are no longer linked to any account and will be removed on request. You can also request a copy of your data, or its deletion, by emailing the address below.
Deleting your account does not cancel a subscription. Cancel it in your App Store or Google Play subscription settings, or it keeps renewing.
Children
Particle is not directed at children under 13.
Changes to this policy
If this policy changes, the updated version will be posted here with a new effective date. For material changes, notice will be given in the app.
Contact
Questions or requests about your data:support@particle-reader.com