The paper presents the findings from a 3-year single-case study conducted in connection with the International Data Spaces (IDS) initiative. The IDS represents a multi-sided platform (MSP) for secure and trusted data exchange, which is governed by an institutionalized alliance of different stakeholder organizations. The paper delivers insights gained during the early stages of the platform’s lifecycle (i.e. the platform design process). More specifically, it provides answers to three research questions, namely how alliance-driven MSPs come into existence and evolve, how different stakeholder groups use certain governance mechanisms during the platform design process, and how this process is influenced by regulatory instruments. By contrasting the case of an alliance-driven MSP with the more common approach of the keystone-driven MSP, the results of the case study suggest that different evolutionary paths can be pursued during the early stages of an MSP’s lifecycle. Furthermore, the IDS initiative considers trust and data sovereignty more relevant regulatory instruments compared to pricing, for example. Finally, the study advances the body of scientific knowledge with regard to data being a boundary resource on MSPs.