1. Overview
Guard2 (site.guard2.app, hereinafter "the App") is an Android device online-status monitoring tool operated by an individual developer. The App helps users monitor whether their Android devices are regularly online and sends email alert notifications when a device has been offline or unlocked for an extended period.
This Privacy Policy explains how the App collects, uses, and protects your information. By using the App you agree to this Policy.
2. Information We Collect
| Type | Detail | How Collected | Purpose |
|---|---|---|---|
| Device Identifier | A randomly generated device ID (format: guard2_timestamp_random) | Generated locally on first launch and stored on-device | Uniquely identify a monitored device and associate heartbeat records |
| Device Nickname | A custom name entered by the user | User input | Identify the device in alert emails |
| Recipient Email(s) | 1–3 email addresses entered by the user | User input | Send heartbeat alerts, recovery notices, and deletion notices |
| Heartbeat Timestamp | The UTC time of each heartbeat report | Automatically recorded by the foreground service | Determine whether the device has been offline for too long |
| Screen-unlock Status | Whether the device was unlocked during the heartbeat period (boolean: true/false) | Android system broadcast ACTION_USER_PRESENT | Detect whether someone is using the device; send alert if not unlocked for 12 h |
3. How We Use Your Information
Collected information is used solely for the following purposes:
- Send device online/offline alert emails to your specified recipient address(es)
- Send an alert when no heartbeat is received for more than 2 hours
- Send an alert when the device has not been unlocked for more than 12 hours
- Send a deletion notice and remove the device record after 48 hours of no heartbeat
- Send a recovery notice when the device returns to normal status
We do not use your information for advertising, user profiling, analytics, or any commercial purpose.
4. Data Storage & Security
The App's backend database is provided by Supabase, stored in their secure cloud infrastructure. All data transmission is encrypted via HTTPS.
Fields stored in the database: device ID, device nickname, recipient email list, last heartbeat time, last unlock time, and alert status flags.
Auto-deletion: When a device has no heartbeat for more than 48 hours, the system permanently deletes all records for that device and notifies recipients. You can also tap "Stop" inside the App at any time to immediately delete your device record.
Email delivery is provided by Resend, used solely to send the alert and notification emails described above. Email content is not stored by Resend.
5. Foreground Service & Permissions
The App uses an Android Foreground Service to maintain background operation for continuous heartbeat monitoring. Permission details:
| Permission | Purpose |
|---|---|
FOREGROUND_SERVICE |
Run a foreground service and display a persistent "monitoring active" notification |
FOREGROUND_SERVICE_HEALTH |
Declare the foreground service type as health monitoring, required by Android 14+ |
WAKE_LOCK |
Prevent CPU sleep so the heartbeat timer fires on schedule even on a locked screen |
POST_NOTIFICATIONS |
Display the persistent foreground service notification (required on Android 13+) |
The App listens to the Android system broadcast ACTION_USER_PRESENT
to detect screen unlock events. Only a boolean (unlocked: yes/no) is recorded per heartbeat period —
no unlock time, frequency, or any other detail is stored.
6. Third-Party Services
The App uses the following third-party services. Please review their respective privacy policies:
- Supabase (database & backend): https://supabase.com/privacy
- Resend (email delivery): https://resend.com/privacy-policy
7. Data Sharing
We do not sell, rent, or share your personal information with any third party, except:
- When you have given explicit consent
- When required by applicable law or regulation
- When sending alert notifications via Resend to the email address(es) you provided (core app function)
8. Your Rights
You have the following controls over your data:
- Stop monitoring: Tap "Stop" in the App to immediately delete all records for that device
- Modify information: Change the device nickname or recipient emails when restarting monitoring
- Automatic deletion: Records are automatically deleted after 48 hours of no heartbeat
To manually request data deletion, contact us with your device ID (shown at the bottom of the App's main screen) and we will process your request within 7 business days.
9. Children's Privacy
The App is not directed at children under the age of 13. We do not knowingly collect personal information from children. If you believe your child has provided personal information to the App, please contact us and we will promptly delete it.
10. Changes to This Policy
This Privacy Policy may be updated from time to time. Updated versions will be published on this page with a revised "Last Updated" date at the top. Continued use of the App constitutes acceptance of the updated Policy.
11. Contact Us
If you have any questions about this Privacy Policy, please contact us: