Privacy Policy

At LinguaCue ("we", "us", or "our"), your privacy and trust are our top priorities. This Privacy Policy explains clearly and transparently how we collect, use, store, and safeguard your information when you use our mobile applications (iOS and Android) and related services (collectively, the "Service").

1. Information We Collect

We only collect the minimum information necessary to provide, sync, and improve your language learning experience:

A. Account & Profile Information

• Guest Usage: You can use LinguaCue completely anonymously as a guest without creating an account or providing an email address. All study progress is stored locally on your device.
• Registered Accounts (Optional): If you choose to enable cross-device cloud sync, we collect your email address and an encrypted user identifier (UID) managed via Google Firebase Authentication or Apple Sign-In.

B. Study Progress & Learning Metrics

• Spaced Repetition Scheduler (FSRS) Data: Review intervals, recall stability, difficulty scores, card mastery levels, active streaks, and study timestamps.
• Track Configuration: Selected language tracks (Japanese, Spanish, German, French), active daily review limits, and audio playback preferences.

C. Device Permissions & Audio Usage

• Microphone (`NSMicrophoneUsageDescription`): Used solely when you tap the interactive microphone button inside conversation missions or pronunciation exercises. Audio is processed directly on your device or via secure, ephemeral speech recognition. We never record background audio, and your voice recordings are never stored or sold.
• Speech Recognition (`NSSpeechRecognitionUsageDescription`): Used strictly to evaluate your spoken responses in real-time during Task-Based Language Teaching (TBLT) exercises.
• Notifications: Optional daily study reminder cues and streak notifications scheduled locally on your device.

D. Diagnostics & Crash Reporting

• To diagnose app crashes and ensure technical stability, we collect anonymized crash stack traces and performance metrics through Firebase Crashlytics. This data does not contain personal identifiers and is used exclusively to resolve bugs.

2. How We Use Your Information

We process your data exclusively for the following purposes:

• Calculating personalized forgetting curves and optimal flashcard review schedules using the FSRS algorithm.
• Synchronizing your learning progress, mastery metrics, and customized decks seamlessly between your devices.
• Providing interactive speech evaluation and conversational feedback during language missions.
• Delivering customer support when you reach out to our team.
• Maintaining security, preventing abuse, and verifying subscription entitlement status.

3. Third-Party Service Providers

We rely on trusted, industry-leading infrastructure partners who adhere to strict data protection standards:

Provider	Purpose	Privacy Safeguards
Google Firebase (Auth, Firestore, Crashlytics)	Account sign-in, cloud sync database, crash reporting	Encrypted in transit (TLS/HTTPS) and at rest (AES-256). GDPR compliant.
Apple App Store / Google Play	In-app purchases and subscription management	Payment credentials are processed directly by Apple and Google. LinguaCue never accesses or stores credit card numbers.
Stripe (Web Checkout)	Secure payment processing for web subscriptions	PCI-DSS Level 1 certified payment gateway.

4. Apple Privacy Manifest (PrivacyInfo.xcprivacy) Compliance

In accordance with Apple's developer privacy requirements, our iOS application includes a cryptographically signed Privacy Manifest declaring:

• No Tracking: NSPrivacyTracking is set to false. LinguaCue does not track user activity across apps or websites owned by other companies.
• UserDefaults Reason (`CA92.1`): Local device storage is accessed exclusively to store user learning preferences, active language track selection, and cached study decks within the app container.
• Declared Data Categories: User ID (App Functionality), Product Interaction (Analytics), Crash Data (Diagnostics), Performance Data (Diagnostics).

5. Data Retention & Deletion Rights

You have full control over your data at all times:

• In-App Immediate Reset: You can instantly wipe all your study progress, cards, and intervals by navigating to Settings → Reset All Learning Data.
• In-App Account Deletion: You can permanently delete your registered account and all associated cloud data by tapping Settings → Delete Account.
• Web Deletion Request: You can submit a deletion request online anytime through our dedicated Account Deletion Portal or by emailing privacy@linguacue.app. Requests are processed within 30 days.

6. Children's Privacy (COPPA Compliance)

LinguaCue is a general audience educational application. We do not knowingly collect personal identifiable information from children under the age of 13. If you believe a child under 13 has provided us with personal information, please contact us immediately, and we will promptly delete the data.

7. International Data Transfers (GDPR & CCPA)

If you reside in the European Economic Area (EEA), United Kingdom, or California, you are entitled to specific rights under the GDPR and CCPA/CPRA, including the right to access, rectify, port, or erase your personal data, and the right to object to processing. Because we do not sell your personal data or share it for cross-context behavioral advertising, you are never subjected to profiling or sale of data.

8. Changes to This Privacy Policy

We may update this Privacy Policy from time to time to reflect improvements in our features or changes in applicable laws. We will notify you of material changes by updating the "Effective Date" at the top of this policy and, where appropriate, through an in-app notice.

9. Contact Us

If you have any questions, concerns, or requests regarding this Privacy Policy or your personal data, please reach out to our privacy officer at:

LinguaCue Data Protection Team
Email: privacy@linguacue.app
Website: https://linguacue.web.app
Support: https://linguacue.web.app/support