Swagger is a tool for API design and documentation.

Mock on the other hand is an actual API creation utility with which you can define endpoints, execute some logic for each endpoint and then return some data to the client. There are other similar features which are covered in the user guide.

Mock is not: - A tool for API Specs or documentation - A GUI tool.

I admit explaining the usefulness of this tool is not the easiest thing.

Any feedback is welcome!