Two basic parts:
-- The proverbial discussion about one's resume, work history, etc.
-- Online 'sandbox' test (i.e. Notepad type interface wherein you are expected to write .Net code)
The first interview is a one-to-one. The 2nd interview was with 2 people.
I am not a fan of these 'online sandbox'-styled interviews. As a developer, we don't write C# code in Notepad. We use Visual Studio. The idea that one should memorize the API in an intellisense environment is a bit much.
I also find that this sandbox-styled interview format tends to limit the type of candidates who will have success (i.e. only candidates who think and work the same). At previous workplaces with strong teams, diverse and disparate thinking was encouraged. You tend to get a better product that way. How one resolved the problem was less important than if someone resolved the problem.