Pretty-print, validate and minify JSON. Errors are reported with the exact line and position.
🔒 This tool runs entirely in your browser. Nothing you enter or upload is sent to our servers.
How to use the JSON Formatter & Validator
- Paste your JSON into the input box.
- Click Format for readable output, or Minify to strip whitespace. Sort keys alphabetically if you want stable diffs.
- If the JSON is invalid, the error message tells you where the problem is.
About this tool
JSON (JavaScript Object Notation) is the standard data format for APIs and configuration files. Minified JSON from an API is hard to read; this tool re-indents it and validates it against the strict JSON spec — trailing commas, single quotes, comments and unquoted keys are all rejected, exactly as a real parser would.
Frequently asked questions
Why does my JSON fail with a trailing comma?
Strict JSON does not allow a comma after the last item in an object or array, even though JavaScript does. Remove it.
Is my data sent anywhere?
No. Parsing and formatting use your browser’s built-in JSON engine; nothing leaves the page.
Can it handle large files?
Yes — files of several megabytes format in a fraction of a second. Very large files may make the text box slow to scroll.