This post follow on one I did earlier this year named "Great Developers, Interviews and Projects".
Yesterday an old colleague of mine sent me a WhatsApp message just before going into and interview for a position relating to Api development specifically on .Net Web Api and asked me what he should know and how to prepare.
Normally Web Api or any api development isn't a position on it's own and generally forms part of a general .Net web developer role, but I guess it can happen that someone is just looking for an Api developer.
My response to this question was to look at the following links as a guideline on questions that could be asked during such an interview:
There are many more sites out there that could help you prepare not only for an Api related interview but anything from Mvc to general .Net development, they are just a Google/Bing search away.
Most important thing I do during and interview is to try and find out how much you know, and if you just remembered answers to questions. I normally ask more than what I interview for, such as design principles in .Net, clean code principles, database questions. General syntax questions of c#. The most difficult thing to do in an interview is to determine how much someone knows and if it's just theory they parrot back.
During an interview it's good to give someone a test, and I think in general this should be expected in any technical interview. The test can either be a physical test where you could expect to write code, or even write code on a white board or paper without the use of internet or visual studio, I prefer the latter, because it shows me that when you are in front of clients pressed to come up with a design, you have the knowledge to demonstrate your plan and structure your thoughts.
In the previous post I mentioned that if you have code to show, or actively contributing to an open source project or even your own personal GitHub project, to me at least, this counts a lot, because you have something tangible to show and in some cases can be more worth than a test during an interview.
The main point is to be well prepared for any interview. Go over the theory relating to the subject matter and ensure you can apply it. Don't stress, it's OK to say you don't know, or you need time to think about it.