JSON Formatter & Validator
Paste JSON, format or minify it, and see the exact line and column of any syntax error — all in your browser, nothing uploaded.
How it works
Paste your JSON
Drop in an API response, a config file, or anything else you need to read or ship.
Format or minify
Pretty-print with your choice of indent for readability, or minify to strip whitespace before it ships.
Fix errors fast
If something's wrong, you get the exact line and column instead of hunting through the document by eye.
What people use a JSON formatter for
JSON shows up everywhere in modern software, and it's rarely pretty by default.
Debugging API responses
Cleaning up config files
Minifying before production
Validating before you send it
Making logs readable
A few things worth knowing
JSON is strict about a handful of things that are easy to get wrong by hand: keys must be double-quoted, trailing commas aren't allowed after the last item in an object or array, and single quotes aren't valid at all. A missing comma or an extra one in the wrong place is the most common reason JSON.parse rejects an otherwise reasonable-looking document — this tool surfaces exactly where that happened instead of leaving you to scan line by line.
Formatting and minifying only ever touch whitespace. The underlying data — every key, value, and type — comes out identical to what went in; nothing is reordered, coerced, or rounded beyond what JavaScript's own number formatting already does. That makes it safe to format a payload for review and then minify it right back down before it ships, with confidence the two are equivalent.
Everything runs locally using your browser's own JSON.parse and JSON.stringify, the same engine functions every JavaScript app already relies on — there's no server round-trip, so nothing you paste here ever leaves your device.
Frequently asked questions
Where does the JSON formatting happen?
Entirely in your browser. Your JSON is parsed and re-printed with JavaScript running locally on your device — nothing is sent to a server, logged, or stored anywhere once you leave the page. That also means it works offline once the page has loaded.
What does the error message actually tell me?
When your JSON is invalid, the tool shows the exact line and column where parsing failed, plus the browser engine's own description of what it expected instead. That's usually enough to spot a missing comma, an unquoted key, or a stray trailing comma without scanning the whole document by eye.
What's the difference between Format and Minify?
Format re-indents your JSON with the spacing you choose (2 spaces, 4 spaces, or tabs) so it's easy to read and diff. Minify strips every bit of insignificant whitespace so the same data takes up less space — useful right before it goes into a production payload or a config file where size matters more than readability.
Can this handle large JSON files?
Yes. Parsing and re-printing JSON is a fast, native operation in every modern browser, so even multi-megabyte input formats in a fraction of a second. For very large input the tool defers the work by one tick so the page stays responsive instead of appearing to freeze.
Does it change the order of keys or the underlying data?
No. Formatting and minifying only change whitespace — key order, values, and types are preserved exactly as parsed. Numbers are re-serialized in JavaScript's standard number format, which matches the original for virtually all real-world JSON.
Is this JSON formatter free to use?
Yes, completely free, with no account, no sign-up, and no limit on how many times you use it.