Apps to UML diagrams

WhiteStarUML is a comprehensive, open-source UML modeling tool designed for software developers and system architects. It supports a wide range of UML diagrams and offers features like code generation and reverse engineering.

UMLet is an open-source, Java-based UML modeling tool designed for both educational purposes and rapid creation of UML diagrams. It supports a wide range of diagram types and offers good integration with popular IDEs.

PlantUML is an open-source tool that allows users to generate a wide variety of UML and other diagram types from a simple human-readable text description. It supports sequences, use case, class, activity, component, state, object, deployment, timing diagrams, and more, making it accessible and efficient for technical documentation and visualization.

Umbrello UML Modeller is a comprehensive, free, and open-source UML diagram tool. It provides robust capabilities for creating a wide range of UML and other modeling diagrams, supporting developers and designers in visualizing complex systems.