I have multiple REST-ful APIs that I'm using as my "back-end". I also have multiple web apps (.NET MVC). These web apps make calls to the APIs for data. So, an object being returned by an API will be the same as the object being expected on the web app side (serialized from JSON of course).
For example, if my web app makes a call to an API for a Customer object, that same object will be used across both the API and web app projects.
So, the question is, how do you manage this scenario (create NuGet packages for shared objects/interfaces, duplicate code, etc.)?