JSON Formatter Transformer
Minified JSON is one long line, which is what APIs send and what humans struggle to read. Paste a payload to pretty-print it with indentation, or catch a syntax error before you spend time chasing a bug that is just a trailing comma. The formatter checks that the text is valid JSON. It does not validate a schema.
How to use the JSON Formatter Transformer
- Paste the payload. Objects, arrays, and raw values are all valid input. Trailing commas and comments are not part of JSON and will fail.
- Format. A valid document is reprinted with stable indentation. An invalid one stops with an error so you can fix the structure.
- Copy or compare. Copy the pretty form into a ticket, or run it through the diff checker against the payload you expected.
When it helps
- API debugging. Expand a curl or log line enough to see which field is missing without opening a full IDE.
- Config review. Pretty-print a generated config before you commit it so the diff stays readable.
Common questions
Why is trailing-comma JSON rejected?
JSON does not allow trailing commas or comments. That syntax is JSON5 or JavaScript. Remove the comma or comment.
Does formatting change key order or numbers?
Key order is preserved by the parse and stringify step in modern browsers. Numbers that cannot be represented exactly in IEEE-754 may change, which is a JSON limitation, not extra rounding in the tool.
Can it pretty-print NDJSON logs?
Paste one JSON value at a time. A file of many objects separated by newlines is not a single JSON document.
Is my payload uploaded?
No. Parsing runs locally. Do not paste secrets on a machine you do not trust.
How is this different from the JSON tree view?
The formatter gives you text. The tree view lets you collapse nested objects. Use both when a payload is deep.
Read the guide: JSON Formatter & Validator: Clean Up Messy JSON in Seconds