kotoba 言葉

Privacy Policy

Last updated: December 11, 2025

Kotoba ("we," "our," or "us") is committed to protecting your privacy. This Privacy Policy explains how we collect, use, disclose, and safeguard your information when you use our mobile application and related services.

Information We Collect

Account Information

When you create an account, we collect information provided by your authentication provider (Google or Apple Sign-in), which may include your name, email address, and profile picture.

Learning Data

We collect and store your vocabulary words, learning progress, review history, and language preferences to provide personalized learning experiences and track your progress.

Chat Conversations

Messages you exchange with our AI language tutor are processed to provide conversation practice and grammar corrections. Chat history is stored to maintain conversation context and improve your learning experience.

Audio Data

If you grant microphone permission, we may process audio data for speech recognition features. Audio data is processed in real-time and is not permanently stored on our servers.

Subscription Information

If you subscribe to Kotoba Pro, payment processing is handled by Apple (App Store) or Google (Play Store). We receive confirmation of your subscription status but do not have access to your payment details.

Device Information

We may collect device identifiers, operating system version, and app version for troubleshooting, analytics, and improving our services.

How We Use Your Information

  • Provide, maintain, and improve our language learning services
  • Personalize your learning experience based on your progress
  • Process and manage your subscription
  • Respond to your inquiries and provide customer support
  • Send important updates about the service
  • Analyze usage patterns to improve our app
  • Prevent fraud and ensure security

Third-Party Services

We use the following third-party services:

  • Firebase (Google) — Authentication and data storage
  • RevenueCat — Subscription management
  • OpenRouter / AI Providers — AI-powered language tutoring
  • Cartesia — Text-to-speech services
  • Vercel Analytics — App performance monitoring

These services have their own privacy policies governing their use of your data.

Data Storage and Security

Your data is stored securely using industry-standard encryption and security practices. We use Firebase, which provides robust security measures including data encryption in transit and at rest.

Data Retention

We retain your data for as long as your account is active or as needed to provide you services. You can request deletion of your account and associated data at any time through the app settings.

Your Rights

You have the right to:

  • Access the personal information we hold about you
  • Request correction of inaccurate data
  • Request deletion of your account and data
  • Export your learning data
  • Opt out of non-essential communications

Children's Privacy

Our service is not directed to children under 13. We do not knowingly collect personal information from children under 13. If you believe we have collected information from a child under 13, please contact us immediately.

Changes to This Policy

We may update this Privacy Policy from time to time. We will notify you of any changes by posting the new Privacy Policy on this page and updating the "Last updated" date.

Contact Us

If you have any questions about this Privacy Policy, please contact us at hello@kotoba.fyi.