This chapter aims to study coopetition in association with two concepts: alliances (dyadic level) and a specific form of inter-organizational networks related to business ecosystems. Establishing an alliance with competitors emphasizes cooperation only. Its unit of analysis is the alliance itself rather than the parent organizations. The concept of coopetition has been employed in the context of inter-organizational networks, whether these be districts, clusters or business ecosystems. However, it has also been applied in the so-called dyadic relations. Coopetition has been analyzed from the perspective of platforms, a term that first appeared in the specialized literature in the late 1980s. Many industrial sectors are inspired by this platform logic. Firms having access to such platforms play a key role in guaranteeing the coordination of actors and in promoting the creation of values. These platforms provide access to resources.