Duper2.1.2

Duper lets you send SMS commands to make a misplaced phone ring or return its GPS position, even without an internet connection. The duper ring command makes the phone ring at maximum volume and flash its light, bypassing silent mode; it is useful when the phone is lost nearby and supports a custom ringtone. The duper locate command returns GPS coordinates by SMS at regular intervals, including during emergencies or when the phone has been lent to someone.

It works entirely offline over SMS, with configurable command prefixes, Ring passwords, ring duration, and location intervals controlling who can trigger actions. Locate requires a dedicated secret, while Ring can have its own optional password and can optionally request SMS confirmation. Flash, sound, and vibration can be toggled, while both modes stop when the phone is unlocked and commands run only while it remains locked. Location messages contain an OpenStreetMap link, long messages are split into multipart SMS, and notifications report accepted or refused commands.

The app operates without an account, server, or cloud service and includes no tracking; Android backup is disabled. Version 2.1.2 brings a major security and privacy update, disabling Ring and Locate by default and adding the dedicated Locate secret. The release also includes reliability fixes and improved GrapheneOS compatibility.

Duper is open-source software in Navigation & Travel, released under GPL-3.0. It supports Android 7.0 and later on arm64-v8a, armeabi-v7a, x86_64, and x86; on Android 13 and later, restricted settings may need to be allowed once in app settings before permissions are granted.