Format and validate JSON

Pretty-print, minify and check JSON for errors.

Files never leave your browser

How to use it

  1. Paste your JSON into the box.
  2. Click Format to indent it readably, or Minify to strip whitespace.
  3. If it is invalid, the error names the exact line and column.

Why it runs in your browser

Most file tools upload your document to a server, process it there and send it back. That means a stranger's machine holds your file, however briefly. This tool does the work locally using JavaScript, so nothing is transmitted. You can check: load the page, turn off your internet, and it still works.

Frequently asked questions

What happens if my JSON is invalid?

You get the line and column where parsing failed, which is usually a trailing comma, a missing quote or a single quote where JSON requires double quotes.

Is my JSON sent to a server?

No. Parsing uses the browser's own JSON engine. Nothing is transmitted, so it is safe to paste configuration or API responses.

Does formatting change my data?

No. It is parsed and re-serialised, so only whitespace changes. Key order is preserved.

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