Lex opens files you choose from the Files app, from the Share Sheet, or over Wi-Fi import. Original files are never copied into Lex or uploaded anywhere — Lex reads them in place, and they stay exactly where you put them.
Privacy
Your books stay yours.
Lex is a reading-first reader for files you already own. By default, nothing about what you read leaves your device — the only data that ever leaves is opt-in analytics and anonymous crash diagnostics, and neither includes your content.
Effective August 21, 2026 · Last updated August 23, 2026
Your books stay yours
Originals stay in the Files app
Lex does not host, store, or distribute any reading content.
What Lex stores on your device
Just enough to read
To operate, Lex keeps lightweight local data on your device: reading progress, settings, bookmarks, highlights, notes, and library metadata such as titles, formats, covers, and where each file lives.
This data stays in the app on your device. Deleting the app removes it.
Optional iCloud sync (Pro)
Apple handles your private database
The Pro iCloud sync feature stores your library metadata, reading progress, bookmarks, highlights, and notes in your personal iCloud private database through Apple's CloudKit. Apple processes and stores that data under Apple's privacy policy, in your iCloud account.
Lex does not upload your original book files to iCloud. Without Pro, no iCloud data is used.
Analytics — off by default
Only what you opt into
Lex sends no analytics unless you turn them on in Settings › Privacy. When enabled, Lex uses hosted Firebase Analytics (Google Analytics for Firebase) to understand which features are used.
What may be sent
- An anonymous app-instance ID
- Limited app and device metadata — app version, device class
- Usage events from a small typed allowlist, such as a feature being opened
- An approximate, coarse region
What is never sent
- IDFA and IDFV
- Document contents, filenames, and titles
- Reading text, highlights, and notes
- Search or query text
- Anything that directly identifies you
You can turn analytics off any time in Settings › Privacy.
Crash diagnostics — always on
Automatic, and independent of analytics
Lex uses Firebase Crashlytics to fix crashes. Fatal crash diagnostics are always enabled and are sent automatically — this is independent of your analytics choice. Declining analytics at onboarding, or turning analytics off in Settings › Privacy, does not stop crash reporting.
What may be sent
- Crash type and stack frames
- App version and OS version
- Device class
- An anonymous installation identifier
What is never sent
- Document contents, filenames, and titles
- Reading text, highlights, and notes
- Search or query text
- Custom keys, custom logs, and user IDs
- Anything that directly identifies you
Under Apple's App Privacy labels, this is Crash Data and Other Diagnostic Data — not linked to you, used for app functionality, and never used for tracking. No custom keys, custom logs, user IDs, or non-fatal error records are collected.
Purchases
One transaction, one third party
The one-time Pro unlock is processed through RevenueCat, which receives the anonymous purchase and entitlement information needed to validate your purchase. RevenueCat never receives your reading data.
Support
Only what you send
If you email support, we receive only the information you choose to include.
No ads. No sale. No tracking.
- No ads. Lex shows no advertising of any kind.
- No sale of personal data. We do not sell personal data.
- No cross-app tracking. Lex does not track you across other apps.
Your choices
You stay in control
- Analytics: Settings › Privacy — on or off, any time.
- Local data: Deleting the app removes the reading data stored on your device.
- iCloud data:Managed through your Apple ID, under Apple's iCloud data controls.
Changes
We'll tell you
If this policy changes, the updated version appears on this page with a new effective date.
Contact
Talk to us
Something here isn't clear?
Write to lex@critiko.com.