PlantUML
Create diagrams based on text files.
Example
gedit example.plantuml
@startuml Alice->Bob : hello note left: this is a first note Bob->Alice : ok note right: this is another note Bob->Bob : I am thinking note left a note can also be defined on several lines end note @enduml
Create the diagram online or in thinlinc via terminal:
$ pantuml example.puml
- Picture: