Kotoba Privacy Policy
Last updated: 5 September 2026
Supermassive (“we”, “us”) operates the Kotoba app on Android and iOS (package / bundle ID kr.supermassive.kotoba; Apple App ID 6808684928). Kotoba is a JLPT vocabulary learning app. You can use it without creating an account. This policy explains what information is processed when you use Kotoba, and how to contact us.
1. Purpose of processing
We process information only to:
- Provide learning, review, quizzes, progress, widgets, and settings on your device
- Send study reminders you choose to enable
- Show ads
- On Android, restore learning data through Android backup if you have Google backup turned on
- On iOS, sync learning data through iCloud when you are signed in to iCloud
- Let you export or import learning data as a kotoba-user-data.json file you choose
- Respond if you contact us about privacy
We do not use this information for other purposes. Supermassive does not operate a Kotoba user-account server.
2. Information we process
Stored on your device. Learning progress, word status, streaks, XP, achievements, daily goal, target level, app language, theme, speech settings, and reminder time stay on your device (SQLite and local preferences). Supermassive does not collect this learning data from the app to our own servers.
Android backup. If Google backup is enabled on your Android device, the learning database and settings may be backed up to your Google account and restored after reinstall. Firebase Cloud Messaging registration is excluded from backup. Restore is handled by Google, not by a Supermassive server. This is not real-time sync across devices.
iCloud (iOS). When you are signed in to iCloud on your device, Kotoba may store a learning-data document and related key-value hints in your iCloud container (iCloud.kr.supermassive.kotoba) so progress can be restored or kept in sync across your Apple devices. That storage is in your Apple account; Supermassive does not operate a separate cloud account for Kotoba. If you are not signed in to iCloud, learning data stays only on the device unless you export a file.
Export and import. You can export or import a kotoba-user-data.json file (settings, language, learning progress, sessions, achievements, and active session). The file you choose is under your control. The same format can be shared between Android and iOS.
Notifications. Local study reminders are scheduled on your device after you allow notifications. On Android, if Firebase Cloud Messaging is used, Google may create a device token so a message can be delivered; Firebase auto-initialization is off by default. On iOS, study reminders use the system local notification scheduler only; Kotoba does not use Firebase Cloud Messaging on iOS.
Advertising (Google AdMob). Kotoba shows an app-opening ad. On Android, an ad may also appear on the exit confirmation dialog; on iOS that dialog does not load a network ad. There is no always-on banner above the tab bar. On Android, in regions that require consent (including the EEA and UK), Google’s User Messaging Platform is shown before the ads SDK is initialized, and where required you can manage ad privacy options in Settings. Google may process advertising identifiers, device and app information, IP address, approximate location, and ad interaction data under Google’s policies.
Other. Home-screen widgets read the same on-device data (via an app group on iOS). Open-source license text may be loaded from GitHub when you open the license screen. Pronunciation uses the device text-to-speech engine. You may share an achievement image through the system share sheet; recipients are under your control.
3. Third parties
We do not sell your personal information. We do not share learning records with other companies for their own marketing. The following services may process data as independent controllers or processors, according to their policies:
- Google AdMob and, on Android, the Google User Messaging Platform
- On Android: Firebase Cloud Messaging, Google Play services, and Android backup
- On iOS: Apple iCloud (when you are signed in)
Google’s privacy policy: https://policies.google.com/privacy
Google advertising: https://policies.google.com/technologies/ads
Apple privacy: https://www.apple.com/legal/privacy/
4. Retention
- On-device learning data: until you reset data in Settings or uninstall the app
- Android backup: according to your Google account and device backup settings
- iCloud copies (iOS): according to your Apple ID / iCloud settings, until you delete the data in the app, remove the app’s iCloud data, or turn off iCloud for Kotoba
- Exported files: under your control on the destination you choose
- Ads and messaging: according to Google’s retention policies
- Email you send us: until the request is resolved
5. Your rights
Depending on where you live, you may have rights to access, correct, delete, or restrict processing of personal information, and to withdraw consent. You can delete on-device learning data with Reset all data in Settings. On iOS, resetting data and signing out of or clearing Kotoba’s iCloud data removes synced copies under your Apple account settings. For other requests, email [email protected]. We may need to confirm that the request comes from you.
6. Age rating and children
Kotoba’s store content rating is suitable for a general audience (IARC 3+ / Everyone on Google Play; App Store age rating as listed for the app). The app does not require an account, and learning data stays on your device or, on iOS when enabled, in your iCloud. We do not collect more personal information from children than this policy describes. A parent or guardian can email us to ask for deletion.
7. International transfers
Google’s services and, on iOS, Apple iCloud may process information outside your country, including in the United States. Those transfers follow each provider’s terms and applicable law.
8. Security
Learning data is kept on the device and, when you use them, on Google backup or Apple iCloud. Ads and Android messaging use Google’s infrastructure. No method of storage or transmission is completely secure.
9. Contact
Privacy officer: Supermassive
Email: [email protected]
For questions, bug reports, and other support, see the Kotoba Support page: https://supermassive.kr/pages/support/kotoba
10. Changes
We will post updates to this page. If a change is material, we will provide notice at least 7 days before it takes effect where required. This policy applies from 5 September 2026.