The software architecture of a software system and the coordination efforts necessary to create such system are intrinsically related. Making changes to components that a large number of other components rely on, the technical core, is usually difficult due to the complexity of the coordination of all involved developers. However, a distinct group of developers effectively help evolving the technical core of software projects. This group of developers is called key developers. In this paper we describe a case study involving the Apache Ant project aimed to identify and characterize key developers in terms of their volume of contribution and social participation. Our results indicated that only 25% of the developers may be considered as key developers. Results also showed that key developers are often active in the developers' mailing list and often fulfilled the coordination requirements that emerged from their development tasks. Finally, we observed that the set of key developers was indistinguishable from the set of top contributors. We expect that this characterization enables further exploration over contribution patterns and the establishment of profiles of FLOSS key developers.