The responses feature is very versatile and can be used as an alternative for custom API's for simple apps/websites that mainly use static content.
Using Responses (and collections) can replace a simple API and can save hundreds of hours of development time on the right project.
Using responses for static content can save many hours when the client wants to change some of that content, instead of having a developer change all the hard coded content and make a new build and have QA release it, the client/PM can change the content themself in NStack. No new build needed, no developer or QA time needed.
You can find examples on how to implement Responses for the following platforms:
A guide about Responses can be found here