StackLab Privacy Policy

Local learning. Lesson progress, memory notes, drawing practice, review schedules, game sample use, theme, and reminder preferences are stored on your device. Signing in does not synchronize learning progress between devices. Removing the app or clearing its data may remove this information. Operating-system backups may separately preserve app data according to your device settings.

Optional accounts. Guest learning does not create a Firebase account. If you choose Google or Apple sign-in, Firebase Authentication processes your sign-in. We store a private Cloud Firestore profile containing your user ID, email (including an Apple relay address when used), optional display name, sign-in provider identifiers, and account/profile timestamps. This supports sign-in and account management, not advertising. Authentication services also process technical information needed to secure sign-in, such as IP addresses and authentication activity.

Sign-in SDK diagnostics. The Google Sign-In SDK declares collection of device-level and user identifiers, other usage data, and other technical data for SDK analytics. These Google Sign-In data may be linked to your identity. Google also processes IP addresses, which may be used to estimate a general location for sign-in fraud prevention. Firebase Authentication and Cloud Firestore collect SDK diagnostic information for analytics without linking those diagnostics to your identity. These SDK purposes are separate from uploading your learning activity: KanjiYama does not upload lesson progress, memory notes, or drawings for analytics. The iOS app does not include Firebase Analytics, Crashlytics, Firebase Performance Monitoring, or an advertising SDK. SDK data is not used for advertising tracking.

Purchases. The store processes payments; we do not receive your complete payment-card information. Subscription product, purchase identifiers, verification data, entitlement status, and expiry are processed to grant, restore, and maintain paid access. In the current iOS app, StoreKit verifies purchases on the device. The app does not upload iOS receipts, transaction identifiers, or entitlement records to our Firebase billing service, and does not link these purchases to a Firebase account. Where server verification is used, a pseudonymous billing identifier binds the purchase to your app account. Store purchase records may be retained for transaction integrity, refunds, fraud prevention, and legally required financial records; they are not used for advertising.

Reminders and reviews. Training reminders are optional local notifications. We request device permission when you enable them. They do not upload a push token or create a marketing mailing list. You can switch them off in the app or device settings. Store review prompts use the platform review service; we do not receive your rating or review text from that prompt.

No advertising or tracking. KanjiYama does not include AdMob, advertising identifiers, or advertising tracking. The AdMob and cloud learning-sync descriptions elsewhere on this shared policy concern other apps when those features are present, and do not describe KanjiYama. KanjiYama does not upload your memory notes or drawings for analytics.

Retention and deletion. Account profiles are kept while the account exists. In-app deletion removes the Firebase sign-in account and its profile and clears learning data on the device where deletion is performed. It does not erase device backups, other devices, or records the store independently maintains. Necessary purchase/security records may be retained for fraud prevention or legal obligations rather than to keep an active user profile. Support messages are used to resolve your request and retained only as needed for that purpose and applicable obligations.

You can request account deletion without reinstalling the app through our account-deletion page. Identity verification may be needed. Deleting an account or app does not cancel a store subscription. Use the store subscription settings to manage or cancel billing.

Questions or privacy requests: support@stacklab.com. Do not email passwords, sign-in codes, or full payment-card details.