JSON Formatter
Format and validate JSON. Free, no signup required.
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How It Works
Paste your raw or minified JSON into the input box
Click Run — invalid JSON will show an error message
Copy the formatted output or use Swap to minify it back
Why Use OneConvertly to JSON Formatter?
100% Private
Your files never leave your device. Everything is processed in your browser.
No Signup Required
Use this tool instantly — no account, no email, no limits.
Works on Any Device
Runs in Chrome, Firefox, Safari, and Edge on desktop and mobile.
Completely Free
No watermarks, no daily caps, no hidden fees.
Frequently Asked Questions
Does my JSON get sent to a server?
No. Formatting runs entirely in your browser using JavaScript. Your data never leaves your device.
What indentation does it use?
The default is 2 spaces, which is the most common convention. This will be configurable in a future update.
Can it validate JSON?
Yes. If your JSON is invalid, an error message is shown with details about what went wrong.
Is there a size limit for JSON input?
There is no hard limit. JSON up to several megabytes formats instantly. Very large files may slow down depending on your device memory.
Can I minify JSON instead of formatting it?
Yes. Use the Swap button to toggle between beautified and minified output. Minified JSON removes all whitespace for the smallest possible string.
Does it work on mobile?
Yes. The formatter works in any modern mobile browser. Paste your JSON, tap Run, and copy the result.
Can I use this for JSON from an API response?
Absolutely. Paste raw API response JSON into the input and get a readable, indented version instantly. Great for debugging REST and GraphQL responses.