We will explore how to boost the usability of web and mobile-web apps by implementing offline-first functionalities, it's the only way to guarantee 100% always on user experience. Low signal or no connectivity should no longer be a blocker for the user, we will discuss the available solutions for caching, in-browser database, and data replication. We will also take a look at how WC such as Polymer and Vaadin Elements help solving those issues out of the box. There will be a live coding demo to see how it's simple to manipulate a large data, completely offline.