Exactly, there are plenty of open source libraries out there, and if you really want to see a great implementation of this in C#, then check out the ServiceStac

Exactly, there are plenty of open source libraries out there, and if you really want to see a great implementation of this in C#, then check out the ServiceStack (runs on Mono as well) authentication providers: https://github.com/ServiceStack/ServiceStack/wiki/Authentication-and-authorization https://github.com/ServiceStack/ServiceStack/wiki/Authentica... It makes OAuth easy peasy.