Abstract. It has become an increasingly common practice that software companies collaborate with external developers to develop a software platform for a shared market, constituting software ecosystems. One main concern in adopting the practice of software ecosystem is how to attract external developers to a platform, and how to establish sustainable collaborative relationships with them. We discuss that explicating and in-depth analysis of developers’ objectives and decision criteria can facilitate the design of sustainable collaborations in software ecosystems. Scenarios from Apple iOS and Google Android ecosystems are used for illustration.