LinguDiary Team ("we", "our", or "us") operates the Lingu Diary mobile application (the "App"). We are committed to protecting your privacy and complying with applicable privacy laws, including the Personal Information Protection Act of South Korea.

1. Information We Collect

1.1 Account Information

• Email address: Used for account creation, authentication, and communication
• Authentication credentials: Managed securely through Supabase

1.2 User-Generated Content

• English diary entries: The content you write in the app
• AI-generated feedback: Corrections, tips, and suggestions provided by our AI service
• Learning statistics: Progress tracking, streaks, vocabulary lists, and achievement data

1.3 Automatically Collected Information

• Device information: Non-identifiable device type and operating system version
• Usage logs: App usage patterns for service improvement
• Error diagnostics: Crash reports and technical errors (non-personal)

1.4 Subscription Information

• Payment processing: All payments are processed exclusively by Apple through the App Store
• We do not collect or store: Credit card information, billing addresses, or any payment details
• Subscription metadata: We receive non-financial transaction metadata from Apple, including Apple transaction ID, product ID (e.g., Plus monthly/yearly), purchase date, and subscription status changes, to provide and manage your subscription
• Subscription status: We track your subscription tier (Free/Plus) to provide appropriate features

2. How We Use Your Information

We use the collected information for the following purposes:

• Service delivery: Provide AI-powered English correction and feedback
• Content storage: Save your diary entries and learning progress
• Feature provision: Track streaks, vocabulary growth, and learning statistics
• Service improvement: Analyze usage patterns to enhance the app
• Customer support: Respond to your inquiries and technical issues
• Account management: Authenticate users and maintain account security

3. Data Sharing and Third-Party Services

3.1 Third-Party Service Providers

We use the following trusted third-party services:

Database & Authentication

• Supabase: Stores your account data, diary entries, and learning statistics
• Purpose: Database hosting and user authentication
• Data processed: Email, diary content, learning data

AI Processing Services

• Third-party AI providers: We use providers such as OpenAI and Google Gemini for AI-powered English correction and feedback. The active provider may change over time as we improve quality, reliability, or cost.
• Purpose: Generate writing corrections and learning tips
• Data processed: Diary entry text only (transmitted via secure API)

3.2 Legal Requirements

We may disclose your information if required by law, court order, or government regulation.

4. International Data Transfers

Your data may be transferred to and processed on servers located outside of South Korea, including:

• Supabase servers: United States
• AI processing: May involve servers in the United States or other countries

We ensure that such transfers comply with applicable data protection laws and that appropriate safeguards are in place.

5. Data Retention and Deletion

5.1 Retention Period

• Active accounts: Data is retained while your account is active
• Deleted accounts: All personally identifiable data is permanently deleted immediately when you delete your account
• Legal obligations: Limited billing metadata is retained in anonymized form as required by Korean commerce laws (see §5.2)

5.2 Account Deletion

You can delete your account at any time through the app's Settings. Upon deletion:

• All diary entries are permanently deleted
• All learning statistics are removed
• Your email and authentication data are erased
• This action is irreversible

However, certain billing records (such as Apple transaction IDs, product IDs, payment dates, and subscription status changes) are retained for up to 5 years as required by Korean commerce laws (e.g., the Act on the Consumer Protection in Electronic Commerce). These records are anonymized at the time of deletion — your account identifier is replaced with a random ID so the records cannot be linked back to you personally. We retain only what is necessary for tax audits, refund processing, and dispute resolution.

Important — Apple subscriptions are not automatically canceled. Deleting your Lingu Diary account does not cancel any active Plus subscription managed by Apple. To stop future renewals, you must cancel directly in your Apple ID settings (Settings → [Your Name] → Subscriptions) before deleting your account, or at apps.apple.com/account/subscriptions.

6. Your Rights

Under applicable privacy laws, you have the right to:

• Access: Request a copy of your personal data
• Correction: Request correction of inaccurate data
• Deletion: Request deletion of your account and data
• Restriction: Request limitation of data processing
• Portability: Request your data in a portable format
• Objection: Object to certain types of data processing

To exercise these rights, contact us at: support.lingudiary@gmail.com

7. Data Security

We implement appropriate technical and organizational measures to protect your data:

• Encryption: Data transmission uses HTTPS/SSL encryption
• Access control: Restricted access to personal data
• Secure authentication: Password hashing and secure session management
• Regular monitoring: Continuous security assessments

However, no method of transmission over the internet is 100% secure. We cannot guarantee absolute security.

8. Children's Privacy

Lingu Diary is not intended for children under 13 years of age. We do not knowingly collect personal information from children. If you believe a child has provided us with personal data, please contact us immediately.

9. Changes to This Privacy Policy

We may update this Privacy Policy from time to time. We will notify you of significant changes through:

• In-app notifications
• Email notifications (if applicable)
• Updated "Last Updated" date at the top of this policy

Your continued use of the app after changes constitutes acceptance of the updated policy.

10. Contact Information

If you have questions, concerns, or requests regarding this Privacy Policy:

LinguDiary Team
Email: support.lingudiary@gmail.com

11. Governing Law

This Privacy Policy is governed by the laws of the Republic of Korea.