PlantUml is an open-source tool in Java to draw UML Diagram. A component that enable developers to quickly create some UML diagram using a simple textual description language.
1. sequence diagram,
2. use case diagram,
3. class diagram,
4. activity diagram,
5. component diagram,
6. state diagram
7. object diagram

Basically you can use this tool to write: sequence diagram, use case diagram, class diagram, activity diagram, component diagram. Diagrams are defined using a simple and intuitive language. They can be generated in PNG or SVG format. It is also possible to generate ASCII art diagrams (only for sequence diagrams).

Requirements:
* Java

The license of this software is Free, you can free download and free use this flowchart & diagram software.