Diagram Designer is a vector graphics editor that allows you to create UML class diagrams, illustrations, flowcharts and slide shows. Developed by Meesoft
License: Free
Diagram Designer excels in creating a variety of diagrams with a lightweight and cross-platform approach, but lacks advanced collaboration features. Mockingbird, on the other hand, is designed for collaborative wireframing with an intuitive interface, though it may not handle detailed diagrams as effectively.