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, thus adding an extra layer of security on local data. Think of it as automation for the Lockdown feature, which temporarily disables biometric unlocking features, but also available for devices running older Android versions behind P.

There is also a Wear OS companion app, which can be used to lock your phone manually while still in range, and both apps can be used just for this if you are not interested in any extra/automated functionality.

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 ("Snooze") a RadiusLocker lock when your chosen locking wearable disconnects, such as:

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

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

πŸ”“ Your phone is charging

Other handy paid features:

πŸ”’ Constant PIN mode, which temporarily disables biometric unlocking and requires PIN on a longer-term basis (until cancelled).

  • Automatically trigger a mode to 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. Smartwatch not required.

  • Manual triggers via Quick Settings tile, Wear OS companion app, or extra launcher icons.

  • Can be cancelled via its notification.

πŸš€ Extra app launcher icons for an immediate lock or starting Constant PIN mode.

  • You can use these for assignment of physical buttons on your phone (compatibility varies). For example, double press of the power button to lock instantly or start Constant PIN mode, instead of launching your camera. Useful if you don't have Wear OS, and want to lock your phone immediately without taking it out of your pocket or doing a restart on your wearable to sever the connection while in proximity.

  • Can be launched by Tasker in the background under custom scenarios of your choosing. Example: When leaving your favourite WIFI network, configured in the Tasker profile, launch the "app" for Constant PIN mode to disable biometrics while out in the world.

⏰ 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 that automatically aborts it when your locking wearable returns.

  • Could text someone with your lost phone's location or have it make noises after the delay period.

  • If Tasker has root, you could perform powerful operations (at your own risk): you could be destructive with your phone's filesystem if your watch doesn't reconnect within a few hours.

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

⌚ Multi-watch mode: if you switch between multiple wearables, set RadiusLocker to lock your phone only after the last remaining locking wearable disconnects. This avoids extra locking if you change to a different watch before leaving the house, for example.

Wear companion app:

There's a free Wear (2.0+) companion app that can be used to manually lock your phone while still in range (overriding any active Snooze state) - both 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 RadiusLocker is not under 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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