How to Format JSON: Pretty Print and Read JSON Easily

JSON doesn't care about whitespace - {"user":{"id":42,"name":"Alice"}} and a nicely indented version of the same object are functionally identical. But one of them is scannable and one isn't. Formatting (also called pretty-printing) is purely a readability transformation, and it's one of the most-used steps in working with JSON day to day.

What formatting actually does

A formatter parses the JSON text into its underlying structure, then re-serializes it with consistent indentation - typically 2 or 4 spaces per nesting level - and a line break after each key-value pair or array item.

{"user":{"id":42,"name":"Alice","roles":["admin","editor"]}}

becomes:

{
  "user": {
    "id": 42,
    "name": "Alice",
    "roles": ["admin", "editor"]
  }
}

Why indentation matters more as nesting grows

For a flat object with two or three fields, formatting barely matters - you can read it either way. The value shows up once you're dealing with a real API response: nested objects several levels deep, arrays of objects, optional fields that may or may not be present. Indentation is what lets your eye track which closing brace belongs to which opening one.

Formatting programmatically

If you already have a parsed JavaScript object rather than raw text, formatting is a built-in one-liner:

JSON.stringify(value, null, 2); // 2-space indent
JSON.stringify(value, null, "\t"); // tab indent

The third argument controls the indentation - a number for that many spaces, or a string (like a tab character) to use literally.

Formatting pasted or malformed JSON

The more common scenario is you have raw JSON text - copied from an API response, a log line, or a config file - and it's either minified or just inconsistently formatted. In that case you need a tool that parses the text first, which also means it'll immediately tell you if something's syntactically wrong before it can format it.

2 spaces vs. 4 spaces vs. tabs

None of these is objectively correct - pick whatever your team's existing style already uses, and be consistent.

When you'd want the opposite: minifying

Formatting is for humans reading the JSON. When JSON is headed over the network as an API payload or into storage, the opposite operation - minifying, stripping all whitespace - reduces payload size. See JSON Pretty Print vs Minify: What's the Difference? for when each makes sense.

Common mistakes

• Trying to format JSON that has a trailing comma or other syntax error - fix the syntax first (see Common JSON Syntax Errors and How to Fix Them).
• Manually re-indenting large JSON by hand instead of using a formatter, which is slow and easy to get wrong on deeply nested structures.
• Committing minified JSON to a config file in a repository, making diffs unreadable for anyone reviewing a small change.

Summary

Formatting JSON is a whitespace-only transformation that turns dense, single-line JSON into something readable by adding consistent indentation and line breaks. It doesn't change the data - it changes how easily a human can scan it, which matters a lot once you're past a few fields of nesting.