FREE ANDROID APP · Version 1.2.1

Install ScreenSentry on your Android phone

ScreenSentry helps you see who touched your armed decoy screen when you weren’t looking. It takes one front-camera photo and then locks the phone. It cannot prove anyone was snooping or view private information.

Android 10 or newer · A front-facing camera is required · Download is free

1. Download and install

1. Open this website on the Android phone you want to protect.
2. Tap the Download button above, then open the downloaded ScreenSentry-Android-v1.2.1.apk file using your browser or Files app.
3. Android may ask you to allow installs from this particular app (for example, Chrome or Files). Only proceed if you trust the source and were expecting to install ScreenSentry. Follow Android’s confirmation to install.
4. After installation, switch off the Install unknown apps permission for your browser or file manager if you temporarily enabled it. Do not disable Android's built-in app security checks.

2. Configure and use

1. Open ScreenSentry and choose a screenshot of your own home screen from the gallery.
2. Allow the front-camera permission.
3. Tap Enable locking and approve the Device Administrator permission. ScreenSentry requests only the lock-device policy.
4. Tap ARM SCREENSENTRY and leave the displayed decoy visible. One touch on the decoy should capture a photo and then lock your phone.
5. Unlock your device to view photos in Pictures/ScreenSentry, using ScreenSentry's view-photo option or your Gallery.

3. What does and doesn't trigger a photo?

Does: the first touch on the decoy screenshot while ScreenSentry is armed and the front camera is ready.

Does not: picking up your phone, using its physical power or volume buttons, or touching Android’s actual home/lock screens. ScreenSentry only detects touches inside its own active screen.

4. Uninstall or disable locking

1. Open ScreenSentry and select Disable locking / Uninstall.
2. Choose Disable locking to keep the app but remove its lock-screen authorization, or Uninstall to remove authorization and open Android's confirmation dialog.
3. If needed, use Android Settings → Security & privacy → Device admin apps → ScreenSentry → Deactivate, then Settings → Apps → ScreenSentry → Uninstall. Exact menu labels vary by phone.
4. Photos saved in Pictures/ScreenSentry may remain after removal. Delete them separately if you no longer need them.

5. Safety and privacy

This app is for protecting a phone you own or are authorized to use. Be mindful of other people’s privacy, and follow applicable law. ScreenSentry stores photos locally and does not send them to the developer. Photos may be included in your phone’s own cloud backups if you enabled those services. See the privacy policy.

6. Verify your download

For users who want to check file integrity, the official v1.2.1 APK has this SHA-256 checksum:

This checksum helps identify changed files. It does not by itself certify the safety of the app. You can also download SHA256SUMS.txt.

7. Voluntary tips

ScreenSentry is free, with no features locked behind payment. If you like the app, you can optionally leave a tip through Ko-fi for the software already provided.

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