We use swagger only to generate the API documentation, for testing the APIs, we use Postman. We don't find an other tools for producing API documentation in web pages and also in pdf files.
To my opinion Swagger Open Source is a very good tool to quickly produce an api documentation, that how I use it.Swagger can also produce an open api file to generate an api for our application server (Inersystems Iris) but we don't use this functionality for now. We plan to use more Swagger features in the future.
We use swagger only to generate the API documentation, for testing the APIs, we use Postman. We don't find an other tools for producing API documentation in web pages and also in pdf files. Postman is a good complement for testing APIs on InterSystems IRIS (a powerful application server and DB manager) which implements these APIs.