Rails is great! …but maintaining client side of a big sass product can be hard in a monolithic, server oriented architecture. UX, performance and code quality usually suffer - which make users unhappy. In a pool of popular framework options we finally chose Ember to rewrite the client side into an SPA - and we never regret it! This talk will cover all the pros and cons of switching from Rails only app to API based backend + Ember JS app and it will try to show why choosing Ember really was a good decision in a particular use case.