Prior to version 3.5 oVirt didn't provided standard API for creating custom modules/extension. There were some parts of oVirt that allowed limited extensibility like UI plugins or VDSM hooks, but not standard solution. In this session we will take a look at new extension API introduced in oVirt 3.5. We will take a look at features this API offers and we will demonstrate how to create new extension. Wwe will also take a look at different functionality in oVirt that already leverage this API, like AAA and logging, and will present our future plans around it.