This study investigates the impact of Generative AI (GenAI) on the creation of software complements in digital platform ecosystems. Based on semi-structured interviews with software developers from both platform owner and complementor perspectives, we examine how GenAI is applied to platform boundary resources, to either support complement creation or boundary resource improvements. Using the inductive “Gioia approach”, we develop a data structure showing that GenAI improves platform access and expands platform owner and complementor capabilities. The findings offer four implications: GenAI can accelerate complement creation across platforms; it acts as a new type of boundary resource, merging technical and knowledge resources into conversational and code generating capabilities; it shifts developer focus from coding to the value of the complement; and it highlights the growing importance of managing and governing complement creation.