Free JSON Formatter and Validator
Paste JSON below to format, validate, or minify it. Everything runs in your browser — nothing is uploaded.
Frequently Asked Questions
Is my JSON uploaded to a server?
No. Formatting, validation, and minification all run entirely in your browser with JavaScript. Your data never leaves your device.
What does "Validate" check?
It checks that your input is syntactically valid JSON per the JSON specification (RFC 8259) — balanced brackets, quoted keys, valid values, and no trailing commas. If it fails, the error message shows where the problem is.
What is the difference between Format and Minify?
Format pretty-prints JSON with indentation and line breaks so it is easy to read. Minify removes all unnecessary whitespace to make the payload as small as possible for transmission or storage.
Why does my JSON fail with a trailing comma error?
Unlike JavaScript object literals, the JSON specification does not allow a comma after the last item in an object or array. Remove the trailing comma and validate again.
Is there a size limit?
There is no hard limit — because processing happens locally, the practical limit is your browser's memory. Files of several megabytes format without issue.