RadiusLocker is a free open-source app that provides automatic phone locking when your smartwatch goes out of range. Developed by merry cache miss studios, this utility helps secure your phone's local data if it gets lost or left behind. It temporarily disables biometric unlocking features like face recognition, voice recognition, and fingerprint scanning until you enter your PIN.

One of the key features of RadiusLocker is the ability to manually trigger a mode that requires your PIN before accessing your phone, ensuring added security in sticky situations. Additionally, you can set the app to automatically activate this mode when you are sleeping, based on your daily wakeup alarm time.

RadiusLocker also offers advanced options to avoid locking when your chosen wearable disconnects. You can specify conditions such as being connected to a specific Wi-Fi network or Bluetooth device, or when your phone is charging.

Other useful features include constant PIN mode, which disables biometric unlocking and requires a PIN on a longer-term basis, lock retry every ~15 minutes if your phone didn't lock due to a snooze, and the ability to lock your phone if the SIM card or power cable is removed.

For users of Wear OS, there is a companion app available to manually lock your phone while still in range.

Please note that RadiusLocker requires the Device Administrator permission and must be removed from the Device Admin list in the OS settings before uninstallation.

For any issues or feedback, you can contact the developer at