A diagram creation tool that supports UML modeling and runs primarily on Linux but also Windows and Irix. The interface is similar to the commercial Microsoft Visio. [Open Source, GPL]

A simple and easy-to-use UML editor, suitable for students and casual users. [Open Source, GPL]

An easy-to-use modeling environment for GNOME, written in Python. [Open Source, GPL]

Code generator, converts UML Class Diagram (XMI and Dia) to C# and VB.NET code. Can also output using XSLT Templates which adds support for almost any language. [Open Source, LGPL]

UML2 modeling tool for Windows, Linux and Mac OS X, supporting code generation and reverse engineering. [Free Software, GPL]

UML modeling tool that includes support for all standard UML 1.4 diagrams. [Open Source, BSD]

Supports popular modeling tools to improve functional design visualization and validation by directly executing UML domain models as web applications that include business logic. [Commercial, Free Trial]

A configurable toolkit for creating domain-specific modeling and program synthesis environments. Developed at Vanderbilt University, Nashville, Tennessee. [Open Source]

Offers tools that supports the UML notation on Macintosh, Windows, and Linux. Capabilities includes system analysis, requirements traceability, and software design. [Commercial]

A UML analysis, design, documentation and project management CASE tool. Includes basic UML models plus testing, metrics, change management, defect tracking and user interface design extensions. By Sparx Systems. [Commercial, Free Trial]