JSON Formatter & Validator
Free online JSON formatter and validator. Beautify with indentation, minify to one line, or validate syntax and see exactly where an error is — a fast helper for API debugging, config files and development. Parsing happens in your browser and your data is never uploaded. DeveloperRuns locally
Use this tool
How to use
- Paste your JSON text into the input box.
- Click “Beautify” to indent it, or “Minify” to strip whitespace and shrink it.
- Click “Validate” to check the syntax without changing the content; errors are explained.
- Click “Example” to load a quick sample.
Frequently asked questions
Does it upload my JSON?
No, parsing and formatting all happen locally in your browser, so API data with sensitive fields never leaves your device.
Why does it say invalid JSON?
Common causes are a trailing comma after the last item, single quotes instead of double quotes, a missing quote, or mismatched brackets. The tool shows the browser's specific error message.
How large a file can it handle?
Ordinary API responses and config files are handled smoothly. Very large files (tens of MB) are limited by browser memory and are best split into chunks.