[Firebase founder] There is a Firebase C# SDK on the way. We've had some other things, that we've been working on for the last year, that are shipping in the next few weeks which have taken priority. After that, we'll be shifting focus to new SDKs (they're a little complicated and take a bit of time to build)

I'm really glad to hear this. I have been loving Firebase for the app I'm making but one of the components has to run in C# and talking to Firebase from the C# app was much more painful than the other Firebase portions of the application.

This would be awesome. Right now I'm experimenting using raw HTTP requests and Newtonsoft.Json as the JSON [de]serializer. I presume that you will make your C# SDK a portable class library so we can use it in iOS and Android apps as well via Xamarin?

"C# SDK" doesn't say much. SilverLight can use C#, WinRT can use C#, .NET can use C#, but that doesn't mean your "C# library" will run everywhere. C# is just the syntax.