JSON Formatter Developer
Pretty-print, validate and tidy JSON with the indentation you prefer.
JSON Formatter is a free online tool that pretty-print, validate and tidy JSON with the indentation you prefer. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Developer
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- 2
- Works offline
- Yes, after the first visit
About JSON Formatter
Formatting JSON is the most common developer chore on the web. This one parses with the browser’s own JSON engine, so what you see matches what your code will see — and nothing is sent anywhere.
How to use it
- Paste the text you want to run through json formatter.
- Set indent and sort keys a→z.
The 2 settings
| Setting | What it does | Default |
|---|---|---|
| Indent | Choose from 3: 2 spaces, 4 spaces, Tab. | 2 spaces |
| Sort keys A→Z | On or off. Off by default. | Off |
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
| Controls | Indent, Sort keys A→Z |
Questions
Is my JSON sent anywhere?
No. It is parsed by your browser's own JSON engine, in the page. That matters because pasted JSON so often contains API keys, tokens and customer records — the exact things you should not paste into someone else's server.
Why does it reject JSON that my code accepts?
Strict JSON forbids trailing commas, single-quoted strings, comments and unquoted keys. Many languages accept those as a convenience; the specification does not. The error message gives you the line and column.
What does sorting keys do to my data?
Nothing semantically — object key order is not meaningful in JSON. Sorting makes two documents comparable in a diff, which is the usual reason to want it.
Two spaces or four?
Two is the prevailing convention in JavaScript and web tooling; four is more common in Python and Java projects. Neither affects the data — pick whatever your repository already uses.