In this paper, we describe a set of tools, based on software engineering, HCI techniques and Java technologies, to support the software development process of 3D Webbased collaborative virtual worlds (CVE) populated by non autonomous interactive entities. This work is a first effort to define a methodology supported by design, analysis and implementation tools that assist the development of Webbased CVE. Our proposal emphasizes on the collaboration aspects among the entities that populate the virtual world and the services that they offer to each other in order to carry out collaboration, rather than modeling and aesthetical aspects of the worlds. This is done from conceptual, operational and implementation points of view. The tools we propose are: a model for the conceptualization of the virtual world under the concept of social groups, a graph-based high level notation to specify the interactions among the entities, and a Java-based software framework that gives support to the model and the interaction graph in order to facilitate the implementation of the CVE. We describe the current implementation of our model. At the end, w e outline how these tools could be part of a methodology for the construction of Web-based CVE and show an example of a CVE developed following the methodology and tools described.