nrfutil is a PC tool which allows for creating and signing firmware packages, as well as for performing the firmware update process using a PC. The tool is used by the nRF5 SDK, and the both protocols in the nRF5 SDK for Thread and Zigbee.

Check Nordic Semiconductor nrfutil GitHub repository for more information about the tool, including about the nrfutil installation.

For the list of available commands, type nrfutil dfu thread --help.