This article aims at describing the role of the open-source software phenomenon within high-tech corporations providing social networks and applications. By taking a multiple case study approach, We address what are the open-source software technological components embedded by leading social networking players, and a rich description on how those players collaborate with the open-source community. Our findings, based on a population of three commercial providers of social networks a suggest that open-source plays an important role on the technological development of their social networking platforms. An open-source technological stack for realizing social networks is proposed and several managerial issues dealing with collaboration with open-source communities are explored.