The rapid growth of social platforms such as Facebook, Twit-ter and LinkedIn underscores the need for people to connect to existing and new contacts for recreational and profes-sional purposes. A parallel of this phenomenon exists in the software development arena as well. Open-source code shar-ing platforms such as GitHub provide the ability to follow people and projects of interest. However, users are manu-ally required to identify projects or other users whom they might be interested in following. We observe that most soft-ware projects use third-party libraries and that developers who contribute to multiple projects often use the same li-brary APIs across projects. Thus, the library APIs seem to be a good fingerprint of their skill set. Hence, we argue that library APIs can form the social glue to connect people and projects having similar interests. We propose APINet, a system that mines API usage profiles from source code version management systems and create a social network of people, projects and libraries. We describe our initial im-plementation that uses data from 568 open-source projects hosted on GitHub. Our system recommends to a user new projects and people that they may be interested in, suggests communities of people who use related libraries and finds experts for a given topic who are closest in a user's social graph. Copyright © 2014 ACM.