This paper explores how customer solution providers leverage digital platform architectures and particularly platform openness to exert control over complex organizational networks. A multiple case-study approach studies three companies with digital platforms that orchestrate solution networks in the LED and ICT industries. Our findings show that the features of product modules (core or peripheral), service modules (relationship intensity and customization), and knowledge modules (explicit, tacit and codified) have differential influence on the levels of platform openness. By managing platform openness of different subsystems accordingly, the solution providers can achieve different control benefits, including ensuring module quality, increasing offering variety, reducing dependence on module providers, and facilitating resource sharing. We contribute to the literature on solution business by reconceptualising the platform approach from a two-level perspective. We also deepen the field's understanding of the role of digital platforms in solution business from an architectural perspective. Recent research in B2B marketing has proposed that solution providers can overcome the challenges of network complexity by adopting a platform approach to network orchestration (Bask, Lipponen,