JSON Formatter & Validator
Paste JSON to validate it and pretty-print it — with the exact line and column of any error.
Validation runs locally as you type — nothing you paste here is sent anywhere. Error positions are read directly from the browser's own JSON parser, so the line and column shown match what your browser sees.
About this tool
JSON Formatter and Validator takes JSON data, checks whether it is valid, and lays it out neatly with indentation so it is easy to read. Developers use it to debug an API response, tidy a configuration file or find the missing comma that breaks a file.
If the JSON has a problem, the tool points out what is wrong, so you can fix it. The work happens in your browser, so your data is not sent anywhere.
How to use it
- Paste your JSON into the input box.
- Run the format or validate action.
- If it is valid, read the neatly indented result and copy it. If not, read the error message and fix the problem it points to.
- Check again until the JSON is valid.
Example
You paste {"name": "Ada", "age": 30,} and the validator reports a problem, because JSON does not allow a comma after the last item. Remove the comma and it becomes valid and is formatted on separate lines.
Tips
- JSON needs double quotes around keys and text. Single quotes are not valid.
- Do not paste secrets such as passwords or keys into any tool you do not control. This one runs in your browser, but it is still a good habit.
Questions people ask
What is JSON?
JSON is a text format for storing and sending structured data. It is used by many websites and apps.
Why is my JSON invalid?
Common causes are a missing or extra comma, single quotes instead of double quotes, or a missing bracket.
Is my data uploaded?
No. It is checked in your browser.
Can it handle large files?
Reasonably large data is fine, but very big files may be slow on a phone.