The pyjson-tricks package brings several pieces of functionality to python handling of json files:
Store and load numpy arrays in human-readable format.
Store and load class instances both generic and customized.
Store and load date/times as a dictionary (including timezone).
Preserve map order {} using OrderedDict.
Allow for comments in json files by starting lines with #.
Sets, complex numbers, Decimal, Fraction, enums, compression, duplicate keys, pathlib Paths ...
As well as compression and disallowing duplicate keys.