What is JSON Validator?
A JSON validator checks whether text follows the JSON grammar defined in RFC 8259. DevKitly runs your input through the browser's native JSON parser, which is the same parser most JavaScript applications use, so a pass here means JSON.parse will accept it.
How to use JSON Validator
- Paste your input into the editor above, or select Sample to load an example.
- Select Validate JSON. If the input cannot be processed, a message explains what to fix.
- Use Copy or Download to take the result with you, and Clear to start again.
Example
Input
{"id": 1, "tags": ["a", "b",]}Output
Error: Unexpected token ']' … (trailing comma after "b")Remove the comma after "b" and the document validates.
Practical use cases
- Check a request body before sending it
- Find the line that breaks a config file
- Confirm generated JSON is valid
Common problems
- Trailing commas after the last item
- Comments inside JSON
- Unescaped double quotes inside strings
Frequently asked questions
Does the validator check a JSON Schema?
No. It checks syntax only. Schema validation (required fields, types) needs a separate schema validator.
Are comments allowed?
Not in standard JSON. Formats such as JSON5 and JSONC allow them, but a strict parser rejects them.
Is JSON Validator free to use?
Yes. JSON Validator is free and does not require an account.
Does my input leave the browser?
No. This tool performs its processing locally in your browser and does not need to upload your input.