Open source is changing how software is built and how money is made. This talk discusses the economics of open source software from the start-up firm, the system integrator, and the software developer perspective. The talk provides a strategy framework and discusses its implementation using the dual-license strategy. It explains how system integrators use open source in the share-of-wallet wars. Finally, open source defines a new developer career. This talk explains this new career and argues that it creates economic value for some while it makes life harder for others.