Format, pretty-print and validate JSON online. Instant error position, 2-space indent, runs in your browser — no extension needed.
| Input | Output |
|---|---|
| {"a":1,"b":[2,3]} | { "a": 1, "b": [ 2, 3 ] } |
| {"a":1,} | Invalid JSON: Unexpected token } |
| [1,2,3] | [ 1, 2, 3 ] |
Same result, no setup: VS Code formats with Shift+Alt+F using the same JSON.stringify re-serialization. This page is for when you are not in an editor — paste, format, copy.
Not for formatting text: paste the JSON here and it is pretty-printed instantly with validation. Browser extensions are only needed to auto-format JSON responses in a tab — for one-off work this page is faster and has no permissions.
The most common causes are trailing commas after the last item, single quotes instead of double quotes, unquoted keys and comments — none of which are legal JSON. The error message shows the exact position of the first problem.
No. Parsing and formatting run entirely in your browser; the text never leaves your device.