Last updated: August 2026
Manabu ("us", "we", or "our") is a Japanese dictionary and study app. This page explains what information the app collects, why, and what happens to it.
The short version: Manabu works fully offline and collects nothing unless you sign in. Signing in exists for one purpose — syncing your study progress across devices — and the account it creates stores no personal identity on our servers: no name, no email address. There are no ads, no tracking SDKs, and your data is never sold or shared for marketing.
Account. You may sign in with Apple or Google. Our server stores only a randomly generated account ID, an opaque identifier from the sign-in provider used to recognize your account on later sign-ins, and session tokens. Your name, email address, and provider profile photo are not sent to or stored on our servers — the app keeps them on your device only, to display on your profile screen.
Study data. When signed in, the app syncs your study progress so it follows you across devices: spaced-repetition scheduling state and review history, per-day study activity totals (time and card counts), favorites, study sets, the study blacklist, and app settings. This data describes your studying, not your identity.
Profile picture. If you choose a custom profile picture, the image you select is resized on-device and uploaded to our server so it can appear on your other devices. It is visible only to your own account.
Local-only data. Dictionary lookups, search history, and reading activity never leave your device. The dictionary itself is bundled with the app, so looking words up requires no network at all.
Your choices. Signing out disconnects your account and keeps your local study data. Deleting your account (Settings → Account) permanently deletes your account and all synced data from our servers. You can also erase local study progress at any time from Settings → Study Progress.
If the app crashes or encounters an error, it may send us an anonymous crash report containing a randomly generated installation ID, your device platform and OS version, the app version, and a technical description of the error. Crash reports are not linked to your account and contain no personal information; they exist solely so problems can be found and fixed.
Like nearly all internet services, our server infrastructure may temporarily process connection metadata (such as IP addresses) as part of ordinary request handling and abuse prevention. We do not use this to profile or track you.
Manabu contains no advertising SDKs and no third-party analytics or tracking. Text-to-speech uses your device's own speech engine — nothing you study is sent anywhere to be spoken.
Three third parties are involved in providing the service: Apple and Google, if you use their sign-in (governed by their own privacy policies), and our hosting provider, Railway, on whose infrastructure the sync server and its database run.
The app does not use cookies. Session authentication uses tokens stored in your device's secure storage (Keychain on iOS, Keystore on Android).
If Manabu or its assets were ever acquired or transferred, synced data may be part of that transfer. Any successor would remain bound by this policy unless you are notified otherwise and given the chance to delete your data first.
All communication with our servers uses HTTPS. Session tokens live in your device's secure storage, and the server keeps no passwords — authentication is delegated entirely to Apple and Google. No method of transmission or storage is 100% secure, but the least risky data is data never collected, which is why the account holds no personal identity in the first place.
Synced data is stored on servers operated by our hosting provider, which may be located outside your country of residence. By using sync, you consent to your study data being processed where those servers run.
If you prefer that nothing leave your device, simply don't sign in — every feature except cross-device sync works without an account.
The app and this site may link to external resources (for example, the dictionary projects credited in Settings → Credits). Their sites have their own privacy practices, which we don't control.
Manabu is not directed at children under 13, and we do not knowingly collect personal information from them. The app stores no name or email for anyone, child or adult; if you believe a child has created an account and want it removed, contact us and we will delete it.
Changes to this policy will be posted on this page with an updated date before taking effect. Continued use of sync after a change takes effect constitutes acceptance of the revised policy.
Questions about this policy, or a data-deletion request you'd rather not do in-app, can be sent through the contact options in the app's Settings → About screen or on this website.