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JSON Formatter & Validator

Format, minify, validate, open, and download JSON with configurable indentation.

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About JSON Formatter & Validator

Format JSON with two spaces, four spaces, or tabs, or minify it in one click. Syntax errors include a line and column when available, and you can open and save JSON files locally.

How to use

1.Paste JSON or open a JSON file from your device.
2.Choose indentation, then format or minify to validate it.
3.Copy the result or download it as a JSON file.

Useful for

Formatting and minifying API responses
Validating configuration files
Opening, checking, and saving JSON files

Verified examples and scope

These examples describe reproducible behavior in this tool. They are not a guarantee for inputs outside the documented scope.

Input or setting	Expected result	Condition
{"name":"Alice","active":true}	JSON formatted with two spaces, four spaces, or tabs	The tool does not intentionally reorder keys or coerce value types.
{"items":[1,2,]}	A JSON syntax error	A trailing array comma is not valid JSON.

Known limitations

Comments, trailing commas, NaN, Infinity, and other non-JSON syntax are rejected.
Opened JSON files are limited to 5 MB.

If the result is unexpected

If no error line and column are shown, the browser-provided parse error did not include a source position.

How it works

Validation uses JSON.parse; formatting and minification use JSON.stringify.

The tool handles values in the JSON syntax described by ECMA-404.

Pasted JSON and opened file contents are processed in the browser.

Input examples

{"name":"Handy Web Tools","active":true}
[{"id":1},{"id":2}]

Notes and limitations

Comments, trailing commas, and single quotes are not valid standard JSON.
Files are limited to 5 MB. When handling sensitive data, also consider the security of your device and browser.

Frequently asked questions

Can it detect invalid JSON?

Yes. The tool reports the line and column of a syntax error when that location is available.

Can I minify and download JSON?

Yes. You can remove unnecessary whitespace and download the result as a JSON file.

Is JSON uploaded to a server?

No. Formatting and validation run in your browser. You should still make sure your own device and browser environment are secure.