ArchStudio 4 (Free Tool) for Modeling, Visualizing, Analyzing, and Implementing Software and Systems Architectures

ArchStudio 4 is definitely worth checking out. It is a free tool modeling tool that integrates with Eclipse.

ArchStudio 4 Overview (from ArchStudio 4 site)
ArchStudio 4 is an open-source software and systems architecture development environment developed by the Institute for Software Research at the University of California, Irvine. It is an environment of integrated tools for modeling, visualizing, analyzing and implementing software and systems architectures. It is based on the Eclipse open development platform. It is released under a BSD-style license.


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Get it here.