Many organisations are dependent upon long-term sustainable software systems and associated communities. In this paper we consider long-term sustainability of Open Source software communities in Open Source software projects involving a fork. There is currently a lack of studies in the literature that address how specific Open Source software communities are affected by a fork. We report from a study aiming to investigate the developer community around the LibreOffice project, which is a fork from the OpenOffice.org project. In so doing, our analysis also covers the OpenOffice.org project and the related Apache OpenOffice project. The results strongly suggest a long-term sustainable LibreOffice community and that there are no signs of stagnation in the LibreOffice project 33 months after the fork. Our analysis provides details on developer communities for the LibreOffice and Apache OpenOffice projects and specifically concerning how they have evolved from the OpenOffice.org community with respect to project activity, developer commitment, and retention of committers over time. Further, we present results from an analysis of first hand experiences from contributors in the LibreOffice community. Findings from our analysis show that Open Source software communities can outlive Open Source software projects and that LibreOffice is perceived by its community as supportive, diversified, and independent. The study contributes new insights concerning challenges related to long-term sustainability of Open Source software communities. 
Sustainability of Open Source software communities beyond a fork: How and why has the LibreOffice project evolved?