JSON Formatter
Format, beautify and validate JSON instantly.
Output will appear here.
What is a JSON Formatter?
A JSON formatter re-indents a JSON document so its structure becomes visible. The data itself does not change — the same keys hold the same values — but line breaks and consistent indentation turn a single-line blob into a tree you can actually scan.
Formatting is also the fastest way to find a syntax error. A parser has to walk the whole document to indent it, so a stray comma, an unquoted key or a missing bracket surfaces immediately, together with the position where parsing stopped.
When you need it
- An API returned a minified response and you need to see which fields it actually contains.
- A log line contains an escaped JSON payload that is unreadable as-is.
- A config file was edited by hand and something in it no longer parses.
- You are writing a bug report and want the payload readable by whoever picks it up.
- Two versions of a document need comparing, and inconsistent formatting makes a plain text diff useless.
How to use the JSON Formatter
- Paste your JSON into the input panel, or load the built-in sample.
- Pick the indentation you want — 2, 4 or 8 spaces.
- Press Format. Readable JSON appears on the right; if the document does not parse, the error and its position appear instead.
- Use Minify to go the other way, or Validate to check the syntax without changing the output.
- Copy the result, or download it as a .json file.
Examples
JSON Formatter features
Frequently asked questions
Does formatting change my data?
No. Only whitespace changes. Keys, values, types and array order are preserved exactly, so the formatted document is semantically identical to the input.
Why does my JSON fail to parse when it looks fine?
The usual causes are a trailing comma after the last item, single quotes instead of double quotes, unquoted object keys, or a stray control character pasted in from a log. All three are legal JavaScript but invalid JSON.
Can it handle large files?
Yes for typical payloads — a few megabytes formats instantly. Very large documents are limited by your browser rather than by the tool.
Are key order and number precision preserved?
Key order is preserved. Numbers are parsed as JavaScript doubles, so integers beyond 2^53 lose precision — for those, treat the value as a string in the source data.
Is my data uploaded to a server?
No. Every iZZi DevTools tool runs inside your browser using the standard web platform. The data you paste is processed on your own machine and is never transmitted, stored or logged by us.
Do I need an account?
No. Every core tool is free, unlimited and works without signing in. An account only adds conveniences such as saved snippets and history.
Does it work offline?
Once the page has loaded, yes. Because the processing happens in the browser rather than on a server, the tool keeps working if your connection drops.