You copy a response out of a browser's dev tools or a Postman request, paste it into a text editor, and it's one unbroken line — 4,000 characters of {"id":1,"name":"... with no line breaks anywhere. Nothing is wrong with the data. It's just not formatted for a human to read.
Why APIs send JSON like this
Whitespace — the line breaks and indentation that make JSON readable — adds bytes to every response with zero effect on what the data means. {"id":1} and { "id": 1 } parse to the exact same object. So most production APIs strip that whitespace out entirely (this is called "minifying") before sending a response, because at scale, saving a few bytes per request across millions of requests actually adds up. It's the right call for a server talking to a program. It's miserable for a person trying to read it.
What "pretty-printing" does
Pretty-printing (sometimes called "beautifying") parses the JSON and re-serializes it with consistent indentation and line breaks — one key per line, nested objects indented further than their parent. It doesn't change a single value; it only changes how the structure is laid out on the page. Minifying is the reverse operation — same data, whitespace stripped back out.
The part that actually catches bugs: validation
Before any of that formatting can happen, the JSON has to actually parse — and that's often the more useful thing a formatter does for you. A missing comma, an unescaped quote inside a string, or a trailing comma after the last item in an object (valid in JavaScript object literals, invalid in strict JSON) will all fail to parse. A good formatter tells you exactly what went wrong instead of leaving you to scan 4,000 characters by eye looking for a missing bracket.
Using the tool
Paste your JSON into our JSON Formatter, choose Pretty or Minify, and run it. If the JSON is invalid, you'll get a specific error message instead of a silent failure. If it's valid, you'll get the reformatted result plus its byte size — handy for checking how much a minified payload actually saves over the pretty-printed version, if you're curious. Nothing you paste is saved; it's processed for that one request only.
Try it here: JSON Formatter.