jq is a command line tool to process JSON documents with loads of features.
If you just want quick (re-)indentation, use one of these Python powered poor man's alternatives:
python -c "import json,sys;json.dump(json.load(sys.stdin),sys.stdout,indent=2)" < data.json
python -c "import json,sys,pprint;pprint.pprint(json.load(sys.stdin))" < data.json