JSON validator
Property name must be a string literal
Processed in your browser · nothing is uploaded
Checks JSON against the actual grammar and points at the first thing that breaks it, with a line and column. The sample above has a trailing comma, which is the single most common cause.
How to use the json validator
This validates syntax, not shape. JSON being valid tells you it parses; it says nothing about whether the fields your code expects are present or the right type. That is schema validation, a separate job done with JSON Schema. The distinction matters because "the JSON is valid" gets offered as a reason an integration should work when the real problem is a missing field or a number sent as a string. If you control both ends, a schema catches those; a syntax validator never will.
Questions
The three usual causes are a trailing comma after the last item, single quotes instead of double, and unquoted keys. All three are valid JavaScript and none is valid JSON.
No. Validity is syntax only. A missing required field or a number sent as a string is valid JSON and still wrong for the endpoint.
A way of describing the expected shape: required fields, types, ranges — so a document can be checked against it. Different from syntax validation.
The standard does not forbid them and most parsers silently keep the last. Avoid them.
No. Parsing and formatting happen in your browser, which matters when the JSON is an API response with real data in it.