JSON Formatter
Paste JSON, get it formatted and validated live — errors come with a line number. Nothing is sent anywhere.
Parsed in your browser — your data never leaves this page.
The four classic JSON mistakes
| Broken | Why |
|---|---|
{"a": 1,} | Trailing comma — remove it |
{'a': 1} | Single quotes — JSON requires double |
{a: 1} | Unquoted key — keys are strings |
{"a": 1 // note} | Comments — JSON has none |
Common questions
How do I format messy JSON?
Paste it in the left box — it pretty-prints automatically with 2-space indentation, or use the Minify button to do the opposite. Validation runs live: if the JSON is broken, you get the error and the approximate line number.
Why is my JSON invalid?
The usual suspects: trailing commas after the last item, single quotes instead of double quotes, unquoted keys, or comments — none of which strict JSON allows. The live error message points at the position.
Is pasted JSON sent to a server?
No — parsing and formatting happen in your browser with the built-in JSON engine. API responses, config files, and customer data never leave your device, which matters when the JSON contains things it usually contains.
What is the difference between formatting and minifying?
Formatting adds indentation and line breaks for human reading; minifying strips every unnecessary character for the smallest payload. Same data, opposite audiences.