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http://marketplace.obeonetwork.com/module/uml ?
You think it is a good and intuitive tool ? You think that something is missing? Fill in this form and help us improve UML Designer.
UML Designer is a free and open source graphical tool to edit and visualize UML 2.4 models. You can easily modify it with Obeo Designer to adapt each diagram to your needs or combine it to your own DSL. Get the source code from our Github :
https://github.com/ObeoNetwork/UML-Modeling