I'll talk about how to use OpenAPI 3 and another tools in production.

JSON is widely used in the current Web. But the request / response format is not in the JSON specification, so we can't guarantee.

In the case of developing API servers for backend server and multiple servers like micro services, guaranteeing the request / response format is improve for stability and development efficiency. So the definition of schema is important.

OpenAPI 3 (formerly Swagger) is a specification for describing the interface of RESTful API. We can define request / response parameters schema for the endpoint using it.

The committee is gem which validates request / response in rack layer. I'm developing the function to perform validation using OpenAPI 3 in this gem. And I shifted my application specification to OpenAPI3 from another schema specification called JSON Hyper-Schema.