Privacy Policy
Last updated: February 18, 2026
1. Overview
MUSD ("the App") is a currency and cryptocurrency conversion tool developed by QIAOZHI LIN ("we", "us", "our"). This Privacy Policy explains how we handle information when you use our App. In short: we do not collect any personal data.
2. Information We Do NOT Collect
The App does not collect, store, process, or transmit any of the following:
- Personal identification information (name, email, phone number)
- Location data or GPS coordinates
- Device identifiers (IDFA, IDFV, or similar)
- Usage analytics or behavioral data
- Cookies or tracking pixels
- Financial or payment information
- Photos, contacts, or any other device data
3. Local Data Storage
The App stores the following data exclusively on your device using iOS local storage (UserDefaults):
- User preferences: language setting, theme selection, selected currencies
- Calculation history: past calculator operations
- Account data: if you create a local account, the username and hashed password are stored only on your device
- Client records: service fee calculation records (stored locally only)
This data never leaves your device unless you explicitly enable iCloud Sync, in which case it is synced via Apple's iCloud Key-Value Store (governed by Apple's privacy policy). We have no access to your iCloud data.
4. Network Requests
The App makes the following network requests to fetch publicly available exchange rate data:
| Purpose | Endpoint | Data Sent |
|---|---|---|
| Fiat exchange rates | api.frankfurter.dev | None (GET request only) |
| Fiat exchange rates | open.er-api.com | None (GET request only) |
| Fiat exchange rates | api.exchangerate-api.com | None (GET request only) |
| Fiat exchange rates | cdn.jsdelivr.net | None (GET request only) |
| Fiat exchange rates | latest.currency-api.pages.dev | None (GET request only) |
| Crypto prices | api.coingecko.com | None (GET request only) |
| Real-time crypto prices | stream.binance.com (WebSocket) | None (subscription message only) |
All requests are read-only. No personal data, device information, or user identifiers are transmitted in any of these requests.
5. Third-Party Services
The App does not integrate any of the following:
- Analytics SDKs (no Google Analytics, Firebase, Mixpanel, etc.)
- Advertising SDKs (no AdMob, Facebook Ads, etc.)
- Crash reporting SDKs (no Crashlytics, Sentry, etc.)
- Social media SDKs
- Any other third-party tracking or data collection tools
6. Children's Privacy
The App does not collect any data from any users, including children under 13. The App is rated 4+ and is suitable for all ages.
7. Data Security
Since we do not collect or store any data on our servers, there is no risk of data breach from our end. Local data on your device is protected by iOS's built-in security features (device passcode, Face ID/Touch ID, encryption at rest).
Local account passwords are hashed using SHA-256 before storage. We never store plaintext passwords.
8. Your Rights
Since we do not collect any personal data:
- There is no data to request, export, or delete from our servers
- You can delete all local App data by uninstalling the App
- You can reset App data from iOS Settings > MUSD
9. Changes to This Policy
We may update this Privacy Policy from time to time. Any changes will be posted on this page with an updated "Last updated" date. Continued use of the App constitutes acceptance of the updated policy.
10. Contact Us
If you have any questions about this Privacy Policy, please contact us:
- Developer: QIAOZHI LIN
- Email: admin098+musdappprivacy@gmail.com