RadiusLocker: Secure your phone when it leaves you

RadiusLocker is a free security app that automatically locks your phone when your smartwatch falls out of connection range, and then temporarily disables biometric unlocking until you've next entered your PIN.

The goal is to further lock down your phone if it gets taken away from you, or if you've left it behind somewhere. Think of it as automation for the Lockdown feature, which temporarily disables biometric unlocking features, but also available for devices running older OS versions behind P.

Choose your locking wearable

Your phone will automatically lock and require PIN to unlock when your smartwatch, fitness tracker, or other wearable is out of range of your phone (i.e. you've lost the device or it was taken). Fingerprint/face/etc unlocking are temporary disabled until a successful PIN entry.

Lock avoidance rules

The phone will not lock from a wearable disconnection under these "Snooze" conditions. It can auto retry locking to check if these conditions are no longer met, and then lock if so.

Additional security and convenience settings

Delay locking in case your smartwatch only temporarily disconnected, launch any Tasker task upon RadiusLocker lock, require authentication to open the app and cancel scheduled lock tasks, perform a lockdown when the SIM card is removed, require PIN to unlock phone 8HR before your alarm time (i.e. you are sleeping), and more.

Full Featureset:

An in-app purchase gives you advanced options to avoid a lock when your chosen wearable disconnects, such as:

πŸ”“ Your phone is connected to a specified WIFI network SSID

πŸ”“ Maps/Waze/Auto is detected as the foreground activity (compatible devices only & is just a "best effort" detection)

πŸ”“ Your phone is connected to another specified Bluetooth device

πŸ”“ Your phone is charging

Other handy paid features:

πŸ”’ Constantly require PIN within 8HR before your phone's alarm, to help prevent others from unlocking your phone using your face or fingerprint while you are sleeping. You don't even need to own a smartwatch to use this mode.

⏰ Lock retry every ~15 minutes if your phone didn't lock due to a Snooze.

⏰ Delay locking by set period in case watch Bluetooth disconnection was temporary and returns after a few seconds.

πŸ”’ Lock if SIM gets removed.

βš™οΈ Launch a Tasker task upon RadiusLocker lock, with an optional delay period in case your locking wearable returns.

πŸ–οΈ Require biometric authentication when cold-launching main app screen or cancelling scheduled lock retry and other events. Offers PIN fallback.


There's a free Wear (2.x+) companion app that can be used to manually lock your phone while still in range (overriding any active Snooze state) - both the RadiusLocker phone and Wear apps need to be installed and fully configured.

Forcing a shutdown on your wearable/smartwatch can also be used to a remotely lock your phone with RadiusLocker, if both devices are still in proximity and not in a Snooze state.

RadiusLocker is designed to be used with Wear devices, fitness trackers, and other wearable devices, though it should be compatible with any generic Bluetooth device you'd want to be used for locking.

RadiusLocker will not work on ZTE devices, as our research has shown that ZTE's implementation of the administrator screen lock doesn't actually disable Smart Lock features.

Because of the Device Administrator permission, later uninstallation first requires you to remove RadiusLocker from the Device Admin list in the OS's settings (searching for Admin should get you there).

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