Collaborative systems help people to overcome constraints of time and space for collaboration. Unfortunately, most of collaborative system developers often face a difficult situation: spending cost, time and effort on network-related problems instead of concentrating collaborative activities. In this paper, we describe the development of CoLib which supports the effective implementation of collaboration clients based on WebDAV. Since the CoLib library encapsulates the complex WebDAV methods and provides collaboration services, collaboration clients with functionality for various group activities can be easily developed.