Format JSON

Paste JSON: it is validated immediately and pretty-printed or minified. Errors show line and column.

Runs only in your browser.

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Frequently asked questions

Is my data sent?

No. The JSON is validated and formatted in your browser. Even credentials in configurations never leave your device.

Do large numbers stay exact?

Yes. Numbers and strings are copied character by character and not converted. Even 20-digit IDs stay unchanged.

Why is my JSON invalid?

Common reasons: a comma after the last entry, single instead of double quotes, comments or keys without quotes. JavaScript allows this, JSON doesn’t.