Software ecosystems (SECOs) driven by platform business models have changed how consumer software is produced and marketed. Also in the enterprise software segment, value networks in the form of SECOs are replacing traditional business models and linear value chains. These SECOs involve three main types of actors: platform sponsor, complementors, and customers. Platform sponsor strategies have been researched broadly, but not the view of complementors. Further, there are few studies of real-world SECOs. In our research, we have investigated the complementor’s perspective on SECOs and their partnership with the platform sponsor. Through exploratory qualitative research using a practical case from the enterprise software industry, we have developed a partner management framework comprising the complementors’ value creation process, goals, enablers, and instruments. The model can be used generally to gain a better understanding of complementors, and by platform sponsors to improve their partner management processes.