The ambivalent paradigm Internet of Things (IoT) is gaining importance in today's industries. To manage the various devices built on different technologies and to apply complex event-triggered business rules to the data streams, platforms are necessary tools for almost all use cases. In the recent years, hundreds of vendors entered the intransparent IoT platform market, from small startups focusing on niches, to large enterprise vendors offering professional solutions. These platforms need tools to orchestrate the interactions between the different sides involved, so-called platform governance mechanisms. The purpose of this multiple case study analysis is to explore the platform governance mechanisms applied in IoT platforms. To achieve this goal, we explored the governance concepts of eight selected platforms in a multiple case study analysis, resulting in a description of the important aspects and differences regarding platform governance. Moreover, the four main trade-offs that platform vendors must be aware of are subsequently discussed. In a last step, an evaluation and discussion of the contribution to theory and practice is provided.