The single page application (SPA) approach has revolutionized our approach to development. Fantastic client-side Javascript frameworks like AngularJS, Knockout, and React have made the transition easy and fun. As we’ve written more and more SPAs an unexpected trend has emerged. We’ve moved to a thin server architecture for delivering our back-end solutions on SPA projects. We increasingly think of the application tier as plumbing, only responsible for data storage with a little authentication, authorization, and validation thrown in.