Is my JSON uploaded anywhere?

No. Parsing happens in your browser via JSON.parse — nothing you paste ever leaves your machine.

What happens if my JSON is invalid?

You get a plain description of what is wrong and the line and column to look at, with the parser’s own message shown underneath it.

Can I change the indentation?

Yes — the formatter supports adjustable indent width for the pretty-printed output.

JSON Formatter

Validate and pretty-print JSON with clear, positioned error messages.

Indent

Input

Output

Formatted JSON appears here.

How it works

Paste JSON into the input box. It is parsed and re-serialized entirely in your browser — nothing is sent to a server — showing a pretty-printed result, or a plain explanation of why it failed to parse, with the parser’s own message underneath, if the JSON is invalid.

Example

Minify → pretty-print

{"a":1,"b":[2,3]}

{
  "a": 1,
  "b": [
    2,
    3
  ]
}

FAQ

Is my JSON uploaded anywhere?: No. Parsing happens in your browser via JSON.parse — nothing you paste ever leaves your machine.
What happens if my JSON is invalid?: You get a plain description of what is wrong and the line and column to look at, with the parser’s own message shown underneath it.
Can I change the indentation?: Yes — the formatter supports adjustable indent width for the pretty-printed output.