JSON Formatter & Validator
Paste any JSON to format it, check it's valid, or minify it down — with a clear error message if something's wrong.
What this tool checks
JSON has strict formatting rules — property names need double quotes, trailing commas aren't allowed, and every bracket needs a matching close. A single misplaced comma or quote breaks the whole thing.
This tool validates your JSON using the browser's own parser, so if it says your JSON is valid, it genuinely is — and if it's invalid, you'll see exactly what went wrong.
Frequently asked questions
Why does my JSON show as invalid?
Common causes: trailing commas, single quotes instead of double quotes, or unquoted property names. JavaScript objects allow these, but strict JSON doesn't.
What's the difference between formatting and minifying?
Formatting adds indentation and line breaks so it's easy to read. Minifying strips all of that out to make the file as small as possible — useful for sending over an API, not for reading.
Is my data uploaded anywhere?
No — everything happens in your browser using JavaScript's built-in JSON parser. Nothing you paste here is sent to our servers.