mtools.lol

JSON Formatter & Validator

Format, validate and minify JSON with clear error messages.

How it works

  1. 1Paste your JSON.
  2. 2Choose format or minify.
  3. 3Copy the result.

Features

  • Validates as you type.
  • Line and column for errors.
  • 2 or 4 space indentation, or minified.
  • Nothing leaves your browser.

Frequently asked questions

Is my JSON sent to a server?

No. Formatting happens entirely in your browser.

Why does my JSON fail to validate?

Common causes are trailing commas, single quotes instead of double quotes, and unquoted keys. The error message shows where parsing stopped.