Contrary to basic logic and common misconceptions, the “X” in XMPP does not stand for “eXtra” or “eXtremely awesome” but for “eXtensible”. This actually tells you a lot about a protocol built to provide reasonable, solid set of of basic features but also a platform for innovative solutions tailored to the project’s needs. The extension mechanism is the heart of this philosophy and also the focus of this talk. We will explore real-life use cases and scenarios where extended XMPP served as a base for a dedicated solution - both for commercial and open-source projects. We will examine different functionalities and components (e.g. inbox, MUCLight, token based reconnection), share experiences, discuss best practices and dissect it all in MongooseIM platform. This talk is not going to take long. As you know, extending XMPP is kinda easy.