Have you used PlantUML? For what types of diagrams?

PlantUML is a tool for creating UML diagrams using simple text descriptions. I have used it to build various types of diagrams, including:

• Class diagrams for modeling system structure and relationships between objects.
• Sequence diagrams for showing interactions over time.
• State diagrams for describing state transitions of objects.
• Component diagrams for visualizing application architecture.

An example of a simple class diagram description in PlantUML:

@startuml
class User {
  +id: int
  +name: string
  +login()
}
class Order {
  +orderId: int
  +date: Date
  +calculateTotal()
}
User "1" -- "*" Order : places
@enduml