Beer Drinkin has an emphasis on code sharing and ensuring that all infrastructure is easily replaceable. If you're looking to get involved with the project, you'll want to become familiar with the architecture of the solution.
The APIs that you'll be interacting with the most will be in BeerDrinkin.Core. This contains all the view models and logic for calling into the other libraries.
Backend Infrastructure
The backend is built on top of Azure App Service but could easily be replaced with another backend provider given the system architecture.
iOS
Built using traditional.
Android
TODO: Build app using Xamarin.Forms
Windows
TODO: Build app using Xamarin.Forms