Software platforms offer a foundation for digital innovation and have the potential to take advantage of and leverage the knowledge and skills of distributed and diverse software organizations as ‘complementors’. Due to their location far away from platform owners, scarce resources, and limited capacity to hire and retain skilled human resources, organizations in developing countries typically face barriers for participating in digital innovation. This paper aims to improve our understanding of how these organizations can take part in digital innovation. The basis for our research is a case study of software organizations located in different developing countries and their role as complementors related to the DHIS2 software platform, a platform made for the public health sector in developing countries. We contribute by exploring and showing how these organizations differ along multiple dimensions, for instance, the maturity of their software development team, their relation to the platform owners, and their access to resources. Further, we identify and develop a taxonomy consisting of six different forms of digital innovation unfolding in the fringes of a software platform ecosystem and identify contextual factors influencing these different forms.