JSON Formatter
Format, minify and validate JSON right in your browser. Nothing is uploaded — it works offline.
This free JSON formatter lets you format JSON online, minify it and validate it against the JSON specification — no upload, no signup. Paste messy JSON on the left and get clean, indented JSON on the right, with the exact line and column of any syntax error.
Reference: RFC 8259 (JSON). Parsing runs on your browser's built-in JSON engine.
How to use the JSON Formatter & Validator
- Paste your JSON into the input box on the left.
- Choose Format, Minify or Validate — or press Ctrl+Enter.
- Copy the result to the clipboard, or load the example to explore.
Frequently asked questions
How do I format JSON online?
Paste your JSON into the box and click Format. The formatter indents and structures the output instantly — the page works offline, so nothing leaves your browser.
Is my JSON data uploaded to a server?
No. Everything runs locally in your browser. Your JSON never touches a server, which makes it safe for configs, logs and API responses.
How can I check if my JSON is valid?
Click Validate. The tool reports the exact line and column of the first syntax error, so you can fix broken JSON fast.
Does it work with large JSON files?
Yes, but files of tens of megabytes are limited by your browser's memory. Typical API payloads and config files are instant.