IBM Rational offers a number of architecture and design products that automate the practice of applying the UML.
Rational products and UML
IBM Rational® Rhapsody® family
A family of model-driven development tools for systems and embedded software using SysML, UML, DDS, UPDM targeting C, C++, Java™, C# and Ada applications.
IBM Rational Software Architect family
A family of model-driven development tools for corporate IT, SOA, and general development, supporting Java, JEE, C++, .NET, SCA, Web 2.0, and more.
IBM Rational Modeler
A free, UML-based software design tool created by one of the founders of Unified Modeling Language.
IBM Rational Rose® family
A family of visual modeling tools leveraging UML for software and systems design.
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Domain specific modeling with IBM Rational Rhapsody