Why format JSON?
APIs and log files often return JSON as a single long line. Formatting (pretty-printing) adds indentation so you can actually read the structure — essential when debugging APIs or exploring a new data source.
Validation helps too
The tool tells you not just that your JSON is invalid, but where the problem is (trailing commas, missing quotes and unclosed brackets are the usual suspects). Minifying does the reverse — strips all whitespace to shrink payloads for production.