Legal
Privacy Policy
1. Who we are
Mojiru is a Japanese language-learning app developed by Rokku Studio and published on the Apple App Store. If you have questions about this policy, contact us at info@mojiru.app.
2. Analytics, tracking, and crash diagnostics
Mojiru has no ads and never tracks you across other apps or websites, so it does not show Apple's App Tracking Transparency prompt. Whether or not you sign in, we never collect:
- Advertising identifiers, or any data used to profile, target, or track you
- Location data
- Your contacts, photos, files, or microphone
To find and fix bugs, Mojiru collects anonymous crash and error diagnostics via Sentry. A report contains your device model, OS version, app version, and the technical details of the crash — never your name, email, or study content. These reports are used only to improve the app, are not linked to your identity, and are never used to track you or for advertising. See Sentry's privacy policy at sentry.io/privacy.
3. Data stored on your device
Mojiru stores all study progress, SRS review history, settings, and statistics locally on your device using SQLite and AsyncStorage. This data never leaves your device unless you sign in and enable cloud sync (see Section 4).
You can delete all on-device app data at any time by deleting Mojiru from your device.
4. Optional account and cloud sync
Mojiru offers optional sign-in via Sign in with Apple, Google, or an email magic link. Creating an account is not required to use the app — it exists solely to back up and restore your progress if you switch or reinstall on a device.
If you create an account, we collect and store the following, all linked to your account and used only to operate the app:
- Email address — used to identify your account and sign you in
- An account identifier (user ID) — a random ID that links your synced data to your account
- Study progress — your SRS review history, kana and vocabulary mastery, JLPT mock-test results, bookmarks, statistics, and app settings
Authentication and cloud storage are provided by Supabase. All data is encrypted in transit (HTTPS) and at rest. We do not sell your data or share it with advertisers.
You can sign out at any time from Settings → Account. You can permanently delete your account and all synced cloud data from Settings → Account → Delete account in the app; you may also email info@mojiru.app. Supabase is a US-based service — see their privacy policy at supabase.com/privacy.
5. Subscriptions (Mojiru Pro)
Mojiru offers an optional Pro subscription via Apple's in-app purchase system, managed by RevenueCat. When you use or purchase a subscription:
- RevenueCat receives your Apple purchase receipt and subscription status to unlock and validate Pro features
- No personal information beyond the purchase receipt and your account identifier is shared with RevenueCat
- Payment is handled entirely by Apple — Mojiru never sees your payment details. See your Apple ID settings to manage or cancel
See RevenueCat's privacy policy at revenuecat.com/privacy.
6. Third-party services
Mojiru uses the following third-party services. None collect personal data on our behalf beyond what is described above:
- Supabase — authentication and cloud sync (only when signed in). Privacy policy
- RevenueCat — subscription management (Pro only). Privacy policy
- Sentry — anonymous crash & error diagnostics. Privacy policy
- Expo / React Native — open-source app framework. No data collection.
7. Children's privacy
Mojiru does not target children under 13 and does not knowingly collect personal information from them. The app contains no advertising or behavioural profiling. In-app purchases (Mojiru Pro) are managed by Apple and require an Apple ID.
8. Changes to this policy
If this policy changes, the updated version will be published at this URL with a new effective date. Significant changes will be noted in the app's release notes.