Software platforms present novel opportunities for innovation across heterogeneous settings, users and areas of use. We report from the case of the Health Information System Programme (HISP) that started out in post-apartheid South Africa more than two decades ago. The programme centres on the development of an open source software – called DHIS2 – primarily for decentralized public health management. Today, DHIS2 is a software platform with a significant global footprint. We contribute to literature on innovation for development, by identifying and examining processes of inclusive innovation pertaining to the longitudinal development of DHIS2. We find that a combination of long-term capacity building and knowledge sharing, consensus-based decision-making, and a modular platform architecture facilitates inclusive innovation. However, short term and project-oriented funding limits the sharing and scale-up of local innovations while the size of the venture and the heterogeneity of actors moderates inclusion in the development of core components of the platform.