In the video above, 96 nRF51 devices are completely erased, programmed with a 150kB .hex file, verified, and reset (application reaches main() when the blue LED lights up) in under 25 seconds. (it takes around 6 seconds to do this for one device using nrfjprog, so this is around 20 times faster than writing a script to do this one at a time).
nRF5_multi_prog program --family NRF51 -e -f s110-bootloader-devicepage-meshapp-merged.hex -v -r
Windows: nRF5-multi-prog.exe since I already have this built. Note that you can just double click make-exec.sh (OS X/Linux) or make-exec.cmd (Windows) in the GitHub repo to build on your computer (requires Python and pip to be installed).
nRF5 Multi Prog is a command line tool to program multiple (up to 127) nRF5 devices concurrently. It was developed to ease Bluetooth Mesh development. It is available as a Python script, command line tool (.exe) and from nRF Connect Mesh (beta release next thursday).
See the right hand side of the screen for nRF5 Multi Prog. Also note that we have a similar tool for RTT logging on our github, where up to 127 devices will log their RTT output to stdout (in nRF Connect this is at the bottom of the screen).
It is multi-platform (Windows, OS X, Linux) and it is open source on Github: https://github.com/NordicSemiconductor/nRF5-multi-prog.
It has a similar interface as nrfjprog with two commands: program and recover. Each command takes multiple arguments. It only works with SEGGER debuggers, but can easily be extended to support pyOCD if requested.