openHAB is a free and open source solution for the smart home. This talk gives an overview of the features of openHAB and shows why open source software is the right answer to the diversity in the smart home. In the quickly growing smart home market, the industry has come up with a vast number of standards, protocols and products. Be it Apple HomeKit, Amazon Echo or Google Home, they usually don't play well together and there is hardly any interoperability across vendors. What is more, the only thing they connect to is their respective cloud service, which lets a typical smart home depend on dozens of remote servers - clearly not a desirable setup as it affects reliability, latency, data privacy, longevity and more. The openHAB project has attracted a huge developer community, which looks at the smart home from a user perspective: This makes features like offline capability, data privacy and customisability top priorities for a smart home solution.