How to use the JSON Formatter & Validator
- Paste your JSON
- Click Format (choose 2 spaces, 4 spaces or tabs) or Minify
- Fix any error at the reported line and column, then copy or download
About this tool
JSON (JavaScript Object Notation, RFC 8259) is strict. Keys need double quotes, trailing commas are not allowed, and comments are not part of the standard. Those three mistakes cause most “invalid JSON” errors. The validator uses your browser’s own JSON.parse, the same parser your JavaScript code uses, and points to the line and column where parsing failed.
Everything runs locally in your browser, so tokens, keys and customer data never leave your device. That matters, because API responses often contain personal data or secrets.
Frequently asked questions
Why is my JSON invalid?
The usual causes are single quotes instead of double quotes, a trailing comma after the last item, unquoted keys, comments, or a missing bracket. The error line shows where the parser gave up. The real mistake is often just before it.
Does sorting keys change my data?
Sorting object keys alphabetically does not change the meaning of JSON, because object key order is not significant. Arrays keep their order.
How large a file can I format?
Several megabytes format in well under a second. Very large files (100 MB+) depend on your device’s memory.
Is it safe to paste API responses?
Yes. Nothing is uploaded. You can turn off your internet connection after the page loads and it still works.
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