Creating SPA and mobile applications by simply putting the logic in the code behind can help you build an initial version of an app quite fast. But in the long run, this architecture will hinder future development. In this talk, I will show you three different software design patterns to provide a better separation of concern: Model-View-ViewModel, Onion Architecture and Clean Architecture. And of course I will not explain this by showing you slides, but we will dive into code to really show you how these patterns work.