Modularizing Android codebases is all the hype these days. It can be as simple as moving a few files, and maybe creating a new build config or two along the way, or it can be much more gruelling. At Spotify, it has meant clearing out years and years of tech debt, re-writing APIs, rethinking the architecture and structure of the application and features that goes into it, wrestling with build tools, and then some. This talk will walk you through the Spotify modularization journey: why we got started, how we went about it, what we have learned through the process, and also why you should be thinking about modilarizing your code, if you haven't already started.