In my last three projects we've aimed at an API first approach, and the flexibility of having the same API serve content for web or native mobile apps is the bi

In my last three projects we've aimed at an API first approach, and the flexibility of having the same API serve content for web or native mobile apps is the biggest win. We used Play on two of this projects and Jersey for another and the speed is very slow at first since the browser has to load a bunch of JS (AngularJS in this case) but then, the whole user experience is seamless. Our biggest problem with this approach were localization and authentication/session handling. Tackling this problems were hard at first and I've never felt confident about the solutions we did for them, specially for authentication.