You're looking for a JSON to VCF (Variant Call Format) converter and an informative paper on the topic. Here's some information:

# Load JSON data with open('input.json') as f: data = json.load(f)

[1] DePristo, M. A., Banks, E., Poplin, R., Gabriel, S., Abecasis, G. R., Gabriel, S., ... & Gabriel, S. (2011). The variant call format (VCF) version 4.0. Nature Precedings, 1-10. doi: 10.1038/npre.2011.6406.1

import json import vcf