The nRF MDK is the microcontroller development kit needed to interact with Nordic Semiconductor's SoCs and SIPs from a 3rd-party IDE.
The nRF MDK provides device support in the form of register header files and startup code to get you started developing with nRF51, nRF52, nRF53 and nRF91 Series devices faster.
It also handles configuration of the supported IDE's built-in programming and debugging tools.
Currently supporting GCC (GNU), IAR Systems, Keil and SEGGER Embedded Studio.
Since version 8.12.0 the nRF MDK has been available under two licenses:
Segger Embedded Studio support
Init code for target device
Register header .h and .c files
Flash and debug config