SDE#
Smart Development Environment (SDE)
SDE Community Edition can be downloaded free, but there is no support for code sync between UML and code, it is merely an embedded VP-UML Community Edition integrated inside the IDE. Only the Professional Edition offers code engineering support.
I have evaluated the SDE for VisualStudio .NET Professional Edition, its C# code synchronization works fine, currently it lacks support for VisualBasic and C++ which Visual Paradigm claims to support in the near future. Its user interface is fully integrated into VisualStudio, looks much like RationalXDE.
Like VP-UML it provides open API for accessing the project UML model and diagrams. Commercial editions provides better interoperability supports through embedding Visio shapes to diagrams, copy and paste to Microsoft Office as OLE, RationalRose project import and XMI import/export.