Privacy Policy
Effective date: April 2, 2026
Developer: Xiaofeng Lei
1. Overview
Kotobi is an AI-powered Japanese learning app. This policy explains what data the app collects, how it is used, and your rights as a user.
Summary: Kotobi stores your study data locally on your device. It does not operate its own user-data servers, does not require an account, and does not sell or share personal data, except when you explicitly use AI features that send content to the AI provider you configure.
2. Data We Collect and How We Use It
2.1 Data stored only on your device
| Data | Purpose | Stored |
|---|---|---|
| Imported PDF and audio files | Source material for sentence extraction and study | On-device only |
| Extracted sentences and study cards | Learning content | On-device database |
| Study progress and review history | Spaced repetition scheduling and progress tracking | On-device database |
| Audio recordings you make | Speaking practice and transcription on request | On-device; deleted after transcription workflow |
| AI API keys | Authenticate requests to the AI provider you choose | Stored locally on device |
| App settings and preferences | Language, provider choice, notifications, and study settings | On-device only |
2.2 Data sent to third-party AI services
When you use AI features, the following data is sent directly to the AI provider whose API key or server you configure. Kotobi does not operate a server that proxies or stores this data.
| Feature | Data sent | Recipient |
|---|---|---|
| Card generation | Japanese sentence text and related prompt content | OpenAI or DeepSeek, depending on user configuration |
| Speaking practice | Audio recording and generated transcript/feedback prompt data | Configured AI provider |
| AI connection test | Short test request | Configured AI provider |
Provider privacy policies:
- OpenAI: openai.com/policies/privacy-policy
- DeepSeek: platform.deepseek.com/downloads/DeepSeek%20Privacy%20Policy.pdf
2.3 Local AI server
If you configure a local AI server on your own network, data is sent only to that server.
3. Permissions
| Permission / Access | Why it is needed |
|---|---|
| Microphone | To record your voice for speaking practice |
| Internet | To reach AI APIs and optional local AI server endpoints |
| Local Network | To connect to a local AI server and support Wi-Fi file transfer |
| Notifications | To send scheduled study reminders when enabled by the user |
4. Data We Do Not Collect
- We do not require user accounts.
- We do not run analytics, advertising SDKs, or tracking tools.
- We do not sell personal data.
- We do not store study data on Kotobi-operated servers.
5. Data Retention and Deletion
Your data remains on your device unless you send content to an AI provider you configured. You can delete data by removing books or cards in the app, deleting app data, or uninstalling the app.
6. Children’s Privacy
Kotobi is not directed to children under 13, and we do not knowingly collect personal data from children under 13.
7. Changes to This Policy
If this policy changes materially, the effective date on this page will be updated.
8. Contact
If you have questions about this privacy policy, contact xiaofeng.lei.bj@gmail.com.
9. App Scope
This policy applies to Kotobi on iPhone / iOS and may also be used for the same app on other supported platforms where the same privacy practices apply.