This looks like a great set of tools to create different types of UML diagrams from simple text representations. Uses Graphviz for some diagram types.
Quoting their website
PlantUML is a component that allows to quickly write :
- Sequence diagram
- Usecase diagram
- Class diagram
- Object diagram
- Activity diagram (here is the legacy syntax)
- Component diagram
- Deployment diagram
- State diagram
- Timing diagram
The following non-UML diagrams are also supported:
- JSON data
- YAML data
- Network diagram (nwdiag)
- Wireframe graphical interface (salt)
- Archimate diagram
- Specification and Description Language (SDL)
- Ditaa diagram
- Gantt diagram
- MindMap diagram
- Work Breakdown Structure diagram (WBS)
- Mathematic with AsciiMath or JLaTeXMath notation
- Entity Relationship diagram (IE/ER)