Privacy Policy
This policy covers the Sentinel Circle app, published by Sentinel Circle ("we"). Effective date: 2026-09-22
Summary
Sentinel Circle runs entirely on your phone. We do not operate any server, and we never receive, store or see any of your information. There are no accounts, no ads, no analytics and no crash reporting. The only information that leaves your phone is:
- the alerts you set up, sent to the recipients you chose;
- the mailbox you ask the Email sensor to check;
- your purchase, which Google Play handles;
- Android's own device backup, if you have it switched on.
What the app handles, and why
Everything below is processed on your phone only. None of it is sent to us.
| Information | Why the app uses it | Where it goes |
|---|---|---|
| Wi-Fi networks nearby (names and identifiers) | The Wi-Fi sensor checks whether a chosen network can still be seen; Sentinel Area learns the networks around it | Nowhere. Read, compared, then discarded; only the network you picked is saved in your settings |
| Bluetooth devices nearby (addresses and names) | The Bluetooth sensor checks whether a chosen beacon is in range; Sentinel Area learns the devices around it | Nowhere. Only the device you picked is saved in your settings |
| Location permission | Android requires location permission to scan for Wi-Fi and Bluetooth. Sentinel Circle does not read, record or use your GPS position | — |
| Notifications from apps you choose | The Notification sensor checks the title and text of notifications from the apps you selected against your filters | Nowhere. Notifications from other apps are ignored at once |
| Email in a mailbox you configure | The Email sensor checks your inbox (IMAP) for messages that match your filters | Nowhere. Messages are read from your mail server and not copied off it |
| Caregiver names, phone numbers and email addresses | Where your alerts are sent | Stored in the app's settings on your phone |
| Mail server passwords | To sign in to your mail server | Stored in Android's encrypted storage on your phone |
| App-lock password | To stop the monitored person changing settings | Only a salted, one-way hash is stored; the password itself is never saved |
| Event log | Shows recent alerts and deliveries | Kept in memory only; gone when the app closes |
What leaves your phone
- Alerts. When a monitor raises an alert or an all-clear, Sentinel Circle sends the message text you wrote (plus the monitor and sensor name) to the recipients you configured. It uses your own phone plan (SMS and phone calls), your own mail server (email), or the WhatsApp app installed on your phone. Those services' own privacy policies apply to messages sent through them.
- Email checking. The Email sensor connects to the mail server you entered, using the account details you gave it.
- Purchases. Upgrading to Standard is handled by Google Play. We only learn from Google Play whether the purchase exists, so we can unlock the features. We receive no payment details. See Google's Privacy Policy.
- Android backup. If Android's automatic backup is on, Android may copy the app's settings (sensors, channels, monitors and caregiver contact details) to your Google account, so they can be restored on a new phone. Passwords, the app-lock state and whether monitoring was running are excluded and never leave the phone. You can switch backup off in Android's settings.
- Configuration export. If you export your configuration, the file goes where you choose to save it. Passwords are only included if you ask for them.
Special permissions
- Accessibility service (WhatsApp channel only). Only if you enable it, Sentinel Circle uses Android's accessibility service to press WhatsApp's Send button for an alert you configured. It acts only inside WhatsApp and only while sending that alert. It does not read, store or send any other screen content.
- Notification access (Notification sensor only). See the table above.
- SMS and phone calls are used only to deliver your alerts, to the numbers you entered. Sentinel Circle does not read your messages or call log.
- Display over other apps lets an alert call start while the app is in the background.
What we share
Nothing. We never receive your information, so we have nothing to sell or share. The app contains no third-party advertising or analytics code.
Keeping and deleting your information
All data stays on your phone until you delete it. To remove everything:
- delete sensors, channels and monitors in the app; or
- clear the app's storage in Android settings; or
- uninstall the app.
Copies you made yourself (exported files, messages already sent, backups in your Google account) are removed through those services.
Security
Passwords are kept in Android's encrypted storage. The app-lock password is stored only as a salted PBKDF2 hash. Connections to mail servers use encryption when your server supports it.
Children
Sentinel Circle is a tool for caregivers and is not directed at children under 13. It does not knowingly collect personal information from children.
Changes to this policy
If this policy changes, we will update this page and its effective date. Any change that affects what leaves your phone will also be noted in the app's release notes.
Contact
Questions about this policy: Sentinel Circle — sentinelcircleapp@gmail.com.