To format/pretty-print a blob of JSON in your clipboard, following methods are available:
Hit CMD+N to create a new document, paste the JSON blob in there, hit CMD+K then M and change the language to JSON. Hit CMD+Shift+P and type and select Format Document.
pbpaste | jq
or
pbpaste | json_pp
import json
s = """<JSON blob>"""
print(json.dumps(json.loads(s), indent=2))
Search for json formatter.