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Privacy Policy

Effective date: 25 May 2026  ·  Last updated: 25 May 2026

1. Introduction

TrayZen ("the App", "we", "us") is a wear-time tracking application for iOS and Android. This Privacy Policy explains what information we collect, how we use it, and your rights under the General Data Protection Regulation (GDPR) and applicable Czech and EU law.

We designed TrayZen with privacy as a default. The app operates entirely on-device for all core features. No personal data is required to use TrayZen.

2. Who we are (data controller)

3. What data we collect

3.1 Data stored on your device (all users)

The following data is stored exclusively on your device using secure local storage (MMKV) and the iOS Keychain. It is never sent to our servers.

  • Wear session timestamps (start/end times) — for timer and history
  • Daily wear goal (hours) — for the goal ring and reminder logic
  • Tracking type (Invisalign / Retainer / Other) — sets goal default
  • Tray change interval and last change date — for tray-change reminders
  • Anonymous device ID (UUID, stored in iOS Keychain) — random identifier, cannot be linked to you without physical device access
  • Notification permission status — determines whether reminders fire
  • App settings (all user preferences) — app configuration only

This data does not include your name, email address, phone number, location, or any other directly identifying information.

3.2 Crash and error reporting

The App uses Firebase Crashlytics (Google LLC) and Sentry (Functional Software, Inc.) to collect anonymous crash reports and error logs. These services receive:

  • Device model and OS version
  • App version
  • Crash stack traces (code locations only — no user content)
  • Temporary session identifiers (not linked to your anonymous UUID)

This data is used solely to identify and fix bugs. It is not linked to your identity and is not used for advertising.

3.3 Analytics

The App uses Firebase Analytics (Google LLC) to collect anonymous usage events (for example: "user toggled timer", "daily goal changed"). These events do not include session content such as timestamps or durations, and cannot be used to identify you. Analytics are used only to understand how features are used and improve the product.

We do not use any advertising analytics, third-party ad networks, or data brokers. We do not sell, rent, or share your data with advertisers.

4. Legal basis for processing (GDPR Art. 6)

  • Local device storage — Legitimate interest (necessary to provide the service)
  • Crash reporting — Legitimate interest (necessary to maintain app safety and quality)
  • Anonymous usage analytics — Legitimate interest (improvement of the product)

5. Data retention

  • On-device data: retained until you delete the app or manually reset your data in Settings. The anonymous Keychain ID survives app deletion on iOS — reinstalling reuses the same ID (standard iOS platform behaviour).
  • Crash reports and analytics: retained according to Firebase's and Sentry's default retention policies (typically 90 days for crash reports, 14 months for analytics events).

6. Your rights (GDPR)

As a data subject under GDPR, you have the right to:

  • Access — request a copy of any data we hold about you.
  • Rectification — request correction of inaccurate data.
  • Erasure — request deletion of your data. On-device data can be deleted by resetting the app in Settings or uninstalling it.
  • Restriction — request that we stop actively processing your data while a dispute is resolved.
  • Portability — receive your data in a machine-readable format.
  • Object — object to processing based on legitimate interests.
  • Lodge a complaint — with the Czech supervisory authority, the Office for Personal Data Protection (ÚOOÚ), if you believe your rights have been violated.

To exercise any of these rights, contact us at support@trayzen.eu. We will respond within 30 days.

7. Cookies

The App does not use cookies. This Privacy Policy applies to the mobile application only. Our website uses no advertising or tracking cookies.

8. Children and age requirements

TrayZen is rated suitable for users aged 10 and up. The app tracks retainer and aligner wear time and contains no age-inappropriate content.

Users under 13 (United States — COPPA) or under 16 (European Union — GDPR) should use the app with the knowledge and consent of a parent or guardian. We do not knowingly collect any personal data from users of any age. The only identifier stored is an anonymous device UUID that cannot be linked to any individual without physical access to the device.

If you believe a child has used the app in a way that raises a privacy concern, contact us at support@trayzen.eu and we will respond promptly.

9. Changes to this policy

We will notify users of material changes to this policy by updating the "Last updated" date and, where appropriate, by displaying a notice in the App. Continued use of the App after changes constitutes acceptance of the updated policy.

10. Contact

For privacy questions or data requests:
Email: support@trayzen.eu