Computer-supported cooperative work (CSCW) supports groups with communication and coordination during the execution of their activities. It allows physically dispersed teams to engage in a common task by providing an interface to a shared workspace. A variety of synchronous applications are playing a major role in distance education, joint program development, cooperative publishing, etc. As these applications are usually platform-dependent, groupware programmers have to develop new applications for each groupware platform. In this paper, we present a collaborative application developing environment called CollabRunJava, which allows the groupware developers to concentrate only on application-specific details. CollabRunJava supports 2 modes for developing applications. In the instant-develop mode, user can immediately execute and test the classes, which are also developed by our system. In the dynamic modify-observe mode, user can observe application behavior, debug applications and c...