nRF Device Firmware Update is a mobile app for updating nRF5 SDK firmware using Bluetooth Low Energy as a transport. It can update the firmware of nRF51 or nRF52 Series SoCs having an nRF5 SDK Secure Bootloader (v12.0.0 or newer) or an nRF5 SDK legacy bootloader (v4.3.0-11.0.0). The firmware should be in .zip file format, prepared using nRF Util (https://github.com/NordicSemiconductor/pc-nrfutil). The firmware can be selected from the local storage on the Android device or downloaded from cloud using a deep-link (see https://github.com/NordicSemiconductor/Android-DFU-Library/#deep-links for details). Note: The app can't be used to update firmware developed with the nRF Connect SDK. In that case then the nRF Connect Device Manager mobile app must be used.