Eighteen months ago, our fairly typical Ruby on Rails app had some mundane client side interactions managed by a tangle of untested JQuery spaghetti. Today, new features are built with React, CSS modules, and a far better UX. With ES6 front end code, processed with Babel, compiled (and hot-reloaded in development) with Webpack, and tested with Jest – all within the same Rails application. Come along to this talk to hear how we migrated our app a piece at a time to use technologies that don’t always sit naturally alongside Rails. I will cover technical implementations and lessons learned.