Developing a cloud computing platform for Big Data: The OpenStack Nova case New developments in virtualization and cloud computing infrastructure keep leveraging the value of Big Data for organizations. In this research, we explore how competing firms collaborate in the development of the OpenStack Nova open-source cloud computing infrastructure. We employ a mix-methods approach that bridges an ethnographic approach with computerized Social Network Analysis (SNA) that data-mines the OpenStack project source-code and its repositories. We take a longitudinal analysis approach that allows us to observe how key events in the competitive cloud computingindustry have affected the development of the Openstack project over time. Our findings capture how companies such as HP, Rackspace, IBM, Mirantis, Vmware, Citrix and many others simultaneously collaborate and compete in a high-networked open-source software project over time. After integrating our findings with the current body of theoretical knowledge in R&D Management, Software Engineering and Open-Source Software, we argue that the established coopetition management theories provide powerful lenses for understanding the competitive and collaborative issues that are simultaneously present and interconnected in the OpenStack open-source project.