Technically, there isn't an "official" OpenAPI 3.x tool of any sort. SmartBear/Swagger is no more official than any other vendor with 3.0+ (obviously it's different for the versions named "Swagger"!). I am working on an official parser/linter (oascomply) on a contract for the OpenAPI Initiative to set a baseline to help tool developers implement consistent support for the spec. However, this is more about the parts of OAS outside of the Schema Object.