Is there a schema for the JSON Schema draft 4 spec?

Question

Is there a JSON schema that describes the JSON Schema draft 4 spec? Ie a schema that describes the format of the schema.

Answer 1

Yes. And it's referenced in the $schema property of JSON schemas:

"$schema": "http://json-schema.org/draft-04/schema#"

From the documentation :

The $schema keyword is both used as a JSON Schema version identifier and the location of a resource which is itself a JSON Schema, which describes any schema written for this particular version.

This keyword MUST be located at the root of a JSON Schema. The value of this keyword MUST be a URI [RFC3986] and a valid JSON Reference [json-reference]; this URI MUST be both absolute and normalized. The resource located at this URI MUST successfully describe itself. It is RECOMMENDED that schema authors include this keyword in their schemas.