What the validator checks
It parses your text with the same rules as JSON.parse and RFC 8259: double-quoted keys and strings, commas between items but not after the last one, no comments, and only true, false and null as literals. Numbers must not have leading zeros, a leading + or a trailing decimal point.
Clear error messages
Browser errors such as Unexpected token only give a character offset. This validator explains the cause in plain words, for example “Missing comma between values” or “Property name is not quoted”, and shows the line with a marker under the problem.
Syntax vs schema
This checks that the text is well-formed JSON. It does not check that the data matches a specific shape (required fields, types); that needs a JSON Schema validator in your code or CI pipeline.
Frequently asked questions
How do I know if my JSON is valid?
Paste it and press Validate. You'll see Valid JSON with a summary, or the line and column of the first error.
Does it validate JSON Schema?
No, it checks JSON syntax only. Use a JSON Schema library such as Ajv (JavaScript) or jsonschema (Python) to check structure.
Why does it only show one error?
A parser can't reliably continue after the first syntax error. Fix it (or press Quick Fix, which repairs many errors at once) and validate again.