GrowNiti LabsDev Tools • Free & private

JSON validator

Check whether JSON is valid. If it isn’t, see the line and column of the first error.

Runs in your browser. Your data is not uploaded or stored.

How to use it

  1. Paste JSON into the input box, or upload a .json file.
  2. A green message means the JSON is valid. A red message gives the line, column and cause of the first error.
  3. Fix the error and the check runs again as you type.

Good to know

  • The most common errors are trailing commas, single quotes instead of double quotes, and keys without quotes.
  • JSON does not allow comments. Remove // or /* */ lines before validating.

About JSON

JSON (JavaScript Object Notation) stores data as nested objects and arrays. It is the standard format for web APIs and the config files of most JavaScript projects.

Questions

Is my data uploaded anywhere?
No. Everything runs in your browser with JavaScript. What you type or paste never leaves your device.
What makes JSON invalid?
Usually a trailing comma, a missing comma between items, single quotes, unquoted keys, or comments. The error message shows the line and column of the first problem.

Privacy

Your data stays on your device

  • Nothing uploaded
  • No account needed
  • No tracking cookies
Read the privacy notice

Every tool runs in your web browser. Text you paste and files you open are processed on your own device. We do not upload, store or sell them, and you do not need an account.

If you switch theme, that choice is saved in your browser so the site remembers it. Pages load fonts from Google Fonts, so your browser connects to Google’s servers to download them. We do not use advertising or tracking cookies; if that changes, this notice will be updated first.

Full privacy policy · grownitilabs@gmail.com

Disclaimer

Free tools, provided as they are

  • Check important results
  • No guarantee
  • Not professional advice
Read the disclaimer

These tools are free and provided as they are, without any warranty. We work hard to make results accurate, but please check anything important before you rely on it, especially converted data, generated passwords and hashes.

The JWT decoder shows what a token contains but does not verify its signature. Nothing on this site is legal, financial or security advice. GrowNiti Labs is not responsible for any loss arising from use of these tools.