PlantUML is an open-source tool allowing users to create UML diagrams from a plain text language. Developed by Arnaud Roques
License: Open Source
Diagram Designer is a user-friendly GUI tool suitable for a variety of diagram types, making it ideal for users who prefer visual design. In contrast, PlantUML is a text-based tool that excels in creating UML diagrams and is favored for its quick edits and integration capabilities, though it requires more technical know-how.