JSON Formatter & Validator
Format, validate, beautify or minify JSON with JavaScript in your browser. Your input stays on this device.
This page is not yet translated into the selected language. The English version is shown; your JSON remains in this browser.
Ready
Paste JSON, drop a file, or open a file to get started.
Formatted JSON appears here. Processing stays in your browser.
Invalid JSON
Private browser processing
Formatting, validation and minification use JavaScript in this browser. The JSON you paste or open is not sent to Convertr servers.
Format for reading
Choose two spaces, four spaces or tabs to make nested objects and arrays easier to scan.
Optional key sorting
Sort object keys recursively while keeping every array item in its original order.
Check numeric and duplicate-key values
JavaScript JSON.parse can round numbers beyond the safe integer range and keeps only the last value for duplicate object keys. Review those limits before saving the result.
Frequently Asked Questions
Is my JSON uploaded to a server?
No. Formatting, validation and minification run with JavaScript in this browser. The JSON you paste or open is not sent to Convertr servers.
What does the validator check?
The validator uses the browser's JSON.parse implementation to check JSON syntax. When the browser includes a position in its parse error, the page shows the line, column and nearby input.
What is the difference between Format and Minify?
Format adds line breaks and indentation for readability. Minify removes unnecessary whitespace from the parsed JSON.
Can I sort object keys alphabetically?
Yes. Sort keys recursively orders object properties, including objects inside arrays. Array item order itself is unchanged.
Can formatting change large numbers or duplicate keys?
It can. JavaScript JSON.parse may round numbers outside the safe integer range, and duplicate object keys are reduced to the last value. The page calls out these limits before you save the output.
Does the formatter support JSON5 or JSONC?
No. JSON.parse follows JSON syntax, so comments and trailing commas are not accepted.
How large a JSON file can I open?
The browser shows a warning before reading files larger than 16 MB because processing a large file may freeze your device. Actual performance depends on the browser and device.