Privacy Policy
Last updated: January 11, 2026
Your privacy is important to us. This policy explains how Zen Kana collects, uses, and protects your information.
1. Data Collection & Usage
Locally Stored Data (Always Collected)
- • Selected characters and vocabulary for practice (up to 5,986 words and 250 kana)
- • Practice session history and statistics across all JLPT levels
- • Performance metrics (accuracy rates, response times, spaced repetition data)
- • User preferences (text scaling, voice input settings, theme preferences)
- • Spaced repetition algorithm data (review intervals, ease factors, learning phases)
- • Custom preset configurations and learning path progress
Cloud Data (Only When Signed In)
- • User authentication credentials (managed by Firebase Authentication)
- • Synced practice progress and statistics across all JLPT levels (N5-N1)
- • User preferences and settings
- • Selected learning items (kana selections and vocabulary selections)
- • Custom presets and learning path progress
- • Device timestamps for conflict resolution
Optional Analytics & Crash Data
Requires explicit consent:
- • App usage patterns (via Firebase Analytics)
- • Feature usage statistics (learning paths, practice modes, preset usage)
- • Crash reports and error logs (via Firebase Crashlytics)
- • Device and platform information (iOS/Android/Web)
Advertising Data (iOS/Android only)
- • Ad interaction data (views, clicks) via Google AdMob
- • Device advertising identifier (optional, can be limited)
- • Non-personalized ads shown by default
- • No personal identifiable information shared with advertisers
- • Note: The Web version is completely ad-free.
2. How We Use Your Data
Primary Uses
- • Learning Progress: Track practice history across 5,986 words and 250 kana characters
- • Spaced Repetition: Calculate optimal review schedules for maximum retention
- • Cross-Device Sync: Enable seamless learning across iOS, Android, and Web (optional)
- • Learning Path Tracking: Monitor progress through Kana Path and JLPT Path systems
Secondary Uses
- • App Improvement: Analyze usage patterns to enhance features (only with consent)
- • Stability: Identify and fix bugs across all platforms (only with consent)
- • Ad Delivery: Show relevant non-intrusive ads every 2nd session on mobile (iOS/Android only)
3. Data Storage
Local Storage:
- • Data stored using SharedPreferences and secure web storage
- • Handles large datasets efficiently (5,986 words + kana data)
- • Persists across app sessions
- • Automatically cleared when app is uninstalled
Cloud Storage:
- • Firebase Firestore database (Google Cloud infrastructure)
- • Data encrypted in transit (TLS/SSL) and at rest (AES-256)
- • Only accessible with your authentication credentials
- • Retained until you delete your account or sign out
4. GDPR Compliance & User Rights
Your Rights
- ✅ Right to Access: View all data we store about you, including complete learning history
- ✅ Right to Rectification: Correct inaccurate data
- ✅ Right to Erasure: Delete your account and all associated cloud data
- ✅ Right to Restriction: Control what data is collected (analytics, crash reports, ads)
- ✅ Right to Data Portability: Export your learning data (learning progress, statistics, presets)
- ✅ Right to Object: Opt-out of analytics, crash reporting, and personalized ads at any time
- ✅ Right to Withdraw Consent: Change consent preferences anytime in settings
Granular Consent Management
Users have individual control over:
- • Analytics Data Collection (Firebase Analytics)
- • Crash Reporting (Firebase Crashlytics)
- • Cloud Synchronization (Firebase Authentication & Firestore)
- • Personalized Ads (AdMob) - Non-personalized by default
5. Advertising Transparency
How Ads Work
- • Frequency: Interstitial (full-screen) ads shown after every 2nd completed practice session
- • Platforms: iOS and Android only (Web version is ad-free)
- • Ad Type: Brief, skippable ads between sessions (never during active practice)
- • Personalization: Non-personalized ads by default; users can enable personalized ads via device settings
- • No Ads During: Active practice, session recovery, settings viewing, or any learning mode content
6. Data Retention
- • Local Data: Stored until app uninstallation or manual data clearing
- • Cloud Data: Retained while account is active; deleted within 30 days of account deletion
- • Analytics Data: Retained according to Firebase policies (14 months, anonymized after 2 months)
- • Crash Reports: Retained for 90 days, then automatically deleted
- • Session Data: Auto-cleanup after 24 hours of inactivity
7. Third-Party Services
Google Firebase Services
- • Authentication (optional)
- • Cloud Firestore (optional)
- • Analytics & Crashlytics (opt-in)
Advertising Services
- • Google AdMob (iOS/Android only)
- • Non-personalized by default
8. Children’s Privacy
The app is suitable for users of all ages. For users under 13 (or applicable age in your jurisdiction):
- • Parental consent strongly recommended before enabling cloud sync
- • Analytics and crash reporting disabled by default
- • No personal information collected without explicit consent
- • COPPA Compliant: No behavioral advertising to children
- • Ad content filtered for age-appropriate material
9. Data Deletion & Contact
How to Delete Data
- 1. Sign out of your account to stop syncing
- 2. Delete account through app settings (Settings → Account → Delete Account)
- 3. Contact support for complete data erasure request
- 4. Uninstalling the app clears all local data
Contact Us
For privacy inquiries, data requests, or to exercise your GDPR rights:
Email: [email protected]
Response Time: Within 30 days as required by GDPR