A JSON formatter that never sees your data
JSON that arrives minified — one long unbroken line from an API response, a log file, or a config export — is genuinely hard to read or debug by eye. This tool reformats it instantly with proper indentation, or does the reverse and strips it down to the smallest possible size, using the browser's own built-in JSON parser. Since JSON frequently contains real data, never uploading it anywhere isn't a nice-to-have here, it's the point.
Using it
- Paste your JSON. It is checked as you type, and an error shows the line and column to look at. "Try a broken example" loads JSON with a trailing comma and single quotes so you can see how errors look.
- Beautify or minify, choosing 2 or 4 spaces of indentation. Tick "Sort keys A–Z" if you want the keys of every object in alphabetical order.
- Copy the result, or download it as a .json file.
Common JSON errors, translated
- Trailing comma: a comma left after the last item in an object or array — valid in JavaScript, invalid in strict JSON. The single most common cause of "unexpected token" errors.
- Single quotes instead of double: JSON strings and keys must use double quotes; single quotes will fail to parse even though they look nearly identical.
- Unquoted keys: object keys need quotes around them —
{name: "value"}is invalid;{"name": "value"}is correct. - A missing closing brace or bracket: the error position reported is often further into the document than where the actual missing character is — worth checking backward from the reported line, not just at it.
Advantages and limitations
Advantages
- Uses the browser's own standards-compliant parser
- Instant — no size limit that requires an upload
- QuickZeta does not upload what you paste, so it suits data you would not post online
Limitations
- Doesn't validate against a specific JSON Schema, only JSON syntax itself
- Error messages use your browser's wording, with a line and column added; the fix is up to you
- Whole numbers with more than 15 digits are rounded when the JSON is rewritten (the tool warns you when this happens)
- Extremely large JSON documents may feel sluggish in an in-browser textarea
Pairs well with
Converting between formats? The site's CSV ⇄ JSON Converter handles that directly, and Hash Generator is useful if you need a quick fingerprint of a specific JSON payload.
Your data stays private
See our Privacy Policy for full details on how QuickZeta handles data.
Frequently asked questions
+Is this JSON formatter really free, with no sign up?
Yes. There's no account and no limit on how much JSON you can format or validate.
+Is my JSON data sent anywhere?
No. Every operation uses the browser's own built-in JSON parser, running directly in your browser — nothing you paste is ever uploaded or logged.
+What's the difference between Beautify and Minify?
Beautify adds indentation and line breaks for readability. Minify strips all unnecessary whitespace to produce the smallest possible file size — what you'd want before actually sending JSON over a network or shipping it in production.
+Does "Sort keys A–Z" change my data?
It only changes the order of keys inside objects. Items inside arrays keep their order, and no values change. JSON objects are unordered by definition, but if another program depends on key order, leave this off.
+Why does my JSON say invalid when it looks fine to me?
JSON's rules are stricter than they look. A trailing comma after the last item, single quotes instead of double quotes, an unquoted object key, or a missing closing brace are the most common causes — all things that are easy to miss scanning by eye but that a parser catches instantly.