nRF Device Firmware Update is a mobile app for updating nRF5 SDK firmware using Bluetooth Low Energy as a transport.
nRF Device Firmware Update 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). It can't be used to update firmware developed with the nRF Connect SDK, then the nRF Connect Device Manager mobile app must be used.
The firmware should be in .zip file format, prepared using nRF Util. The firmware can be selected from the local storage on your Android or iOS device or downloaded from the cloud using a deep-link.