Free JSON Formatter & Validator
This JSON tool validates pasted JSON against the standard grammar, beautifies it with readable indentation, or minifies it for transfer, with plain-English error messages when parsing fails. It is designed for developers debugging API responses, students learning data formats, and website owners fixing configuration files. Nothing is uploaded.
How it works
Input is parsed with the browser's native JSON parser, the same strict grammar every system uses. Formatting re-serialises with 2-space indentation; minifying re-serialises with none. Validation reports success plus the parsed type (object, array, etc.), or the parser's error message pinpointing the failure.
Example
| Minified | Formatted |
|---|---|
{"a":1,"b":[2,3]} | {
"a": 1,
"b": [2, 3]
} |
Frequently asked questions
How do I check if JSON is valid?
Paste it and press Validate. The tool parses with the standard JSON grammar and reports the exact error when parsing fails.
What is the difference between formatting and minifying?
Formatting adds indentation for humans; minifying strips whitespace for the smallest network payload.
Why does my JSON fail on trailing commas?
The JSON specification forbids trailing commas, unlike JavaScript. Remove the comma after the last item.
Can I use single quotes in JSON?
No. JSON strings require double quotes, single-quoted text is invalid even where JavaScript accepts it.
Is my JSON uploaded?
No. Parsing and formatting happen locally in your browser.
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- Guide: JSON Explained for Beginners