"swagger-codegen contains a template-driven engine to generate documentation, API clients and server stubs in different languages by parsing your OpenAPI / Swagger definition."
For many languages... requires java to generate code
Another one in GoLang:
"This package contains a golang implementation of Swagger 2.0 (aka OpenAPI 2.0): it knows how to serialize and deserialize swagger specifications.
Swagger is a simple yet powerful representation of your RESTful API."