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C4 (PlantUML)

C4-PlantUML adds people, containers, and relationships on top of PlantUML. Use diagram_type: c4plantuml and include the stdlib URLs as in the example below (Kroki resolves them at render time).

Example

@startuml
!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Container.puml

Person(user, "User")
System_Boundary(c1, "UML-MCP") {
  Container(api, "FastAPI app", "Python")
  Container(mcp, "MCP server", "FastMCP")
}
Rel(user, api, "HTTPS")
Rel(api, mcp, "HTTP /mcp")
@enduml

Parameters

Property Value
diagram_type c4plantuml
Backend PlantUML with C4 includes
Output formats png, svg, pdf, txt, base64

See also