How to Format and Validate JSON (Free Online)
3 min read
Minified or hand-edited JSON is painful to read and easy to break with a stray comma. Formatting it makes the structure obvious, and validating it pinpoints exactly where it's invalid.
Here's how to format and validate JSON for free in your browser.
Step by step
- 1Paste your JSON
Open the JSON Formatter and paste your JSON into the box. It's processed locally — nothing is sent anywhere.
- 2Format or minify
Click Format to beautify it with clean indentation (2 spaces, 4 spaces, or tabs), or Minify to strip whitespace for the smallest size.
- 3Find errors fast
If the JSON is invalid, the tool shows the parser's message plus the exact line and column — usually a missing comma, trailing comma, or unquoted key.
- 4Copy or download
Copy the cleaned JSON to your clipboard or download it as a .json file.
Tips
- Common JSON errors: trailing commas, single quotes instead of double, and unquoted keys.
- Minify JSON for production payloads and config; format it for reading and debugging.
- Everything runs in your browser, so you can safely paste sensitive data.
Frequently asked questions
How do I fix invalid JSON?
Paste it into the formatter and click Format. If it's invalid, it shows the exact line and column of the error — typically a missing or trailing comma, or unquoted keys.
What does minifying JSON do?
It removes all whitespace and line breaks to make the file as small as possible, useful for APIs and storage. Formatting does the opposite for readability.
Is my data private?
Yes. Everything runs in your browser, so the JSON you paste is never uploaded or stored.