JSON to validate
Valid JSON
Parses cleanly against the strict grammar, so this will go through JSON.parse and any standard JSON library.
Looks good. See it formatted in the Formatter or explore it in the Tree Viewer.
What makes JSON “valid”?
Valid JSON follows the grammar defined in RFC 8259: object keys must be double-quoted strings, no comments are allowed, arrays and objects can't end with a trailing comma, and strings must escape control characters. ToolJar's validator implements this grammar directly rather than relaxing it, so a document that passes here is guaranteed to work with any standards-compliant JSON parser; it won't silently accept malformed input and call it valid.
Questions
It looks fine to me: why is it invalid?
Usually one of four things: a trailing comma, single quotes instead of double, an unquoted key, or a comment. All of them are fine in a JavaScript object literal, which is why they look right. None of them are legal JSON. The error above points at the exact spot.
Does this check my data against a schema?
No. This only answers "is this JSON at all". Whether a required field is missing or a value is the wrong type is a separate question, and you'd want a JSON Schema validator with your own schema for that.