how to create image-flasher.json

I want to create image-flasher.json from the image flasher.
I wanted to know if there is a specific application balena team uses to create that ?

here is an example of image-flasher.json
{ "resin.img": { "parts": [ { "filename": "part-0.deflate", "crc": 2878807330, "len": 4194304, "zLen": 4456 }, { "filename": "part-1.deflate", "crc": 2448150079, "len": 41943040, "zLen": 718460, "partitionIndex": "(1)" },