Update: 2020-05-05: Although it was possible to embed plantuml diagrams into markdown. As of today this does not seem to work wiithout URL encoding the PlantUml content.
It is possible to embed UML diagrams into Jekyll or Markdorn pages using the Gravizo image generation service.
You don’t have to install any local Gems or plugins to embed such diagrams in your Jakyll pages.
Here are some sample UML diagrams:
![Alt text](http://g.gravizo.com/svg? @startuml; Object <|-- ArrayList; Object : equals%28%29; ArrayList : Object elementData; ArrayList : size%28%29; @enduml )
![Alt text](http://g.gravizo.com/svg? @startuml; actor User; participant "First Class" as A; participant "Second Class" as B; participant "Last Class" as C; User -> A: DoWork; activate A; A -> B: Create Request; activate B; B -> C: DoWork; activate C; C --> B: WorkDone; destroy C; B --> A: Request Created; deactivate B; A --> User: Done; deactivate A; @enduml)