Violet is a UML editor with these benefits: Very easy to learn and use. Draws nice-looking diagrams. Completely free. Cross-platform. Violet is intended for developers, students, teachers, and authors who need to produce simple UML diagrams quickly.
Want to contribute ? Source code is hosted on github : https://github.com/violetumleditor/violetumleditor
The concept is good, but it has some severe bugs and development seems dramatically stalled.
Very clean design and has a very stable feel about it. Some simple improvements are needed. For example, you can't center the text inside objects and that is something important for good looking diagrams. Most programs default to centered text. This program is ideal for presentations and papers, and less so for serious developers. I have to add that when the rubber met the road I had to abandon using Violet for serious use. For example, I needed to make a state diagram with about 8 states and needed to label the transitions. The labels cannot be moved relative to the transition, so it was impossible to make a readable diagram because the labels ended up all over the place. :( Still keeping it around when I need a nice looking and simple diagram for documentation or presentations. I have gone back to my old standby of ArgoUML.
I thought I could use violet to do activity diagram, I found out it is pretty useless as there is a serious bug with the "decision" component. if you change the property of one decision , it changes all the properties of all existing "decision" components, thus rendering your diagram useless. or as soon as you change the property of one decision, the next decision that you add to your diagram is set to the same property value, and then because of the problem I mentioned above, you cannot fix it, because everytime you change it to something, Violet changes every property for all the other decisions in your diagram.