Attaching/creating an API for ZProjects?

Attaching/creating an API for ZProjects?

I am not sure where to post this. So I'll try here.

If I have read the explanations correctly, there are a group of people who build APIs, is this correct? These are things like a plug-in? I would like to know more about this - specifically, if I wanted a special function or collection of functions put together in a plug-in, what conditions would apply re. being able to request this or being able to do the building myself, and ownership of the intellectual property?