plantuml-syntax

Original：🇺🇸 English
Translated

Authoritative reference for PlantUML diagram syntax. Provides UML and non-UML diagram types, syntax patterns, examples, and setup guidance for generating accurate PlantUML diagrams.

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Sourcemelodic-software/claude-code-plugins
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NPX Install

npx skill4agent add melodic-software/claude-code-plugins plantuml-syntax

Tags

Translated version includes tags in frontmatter
plantuml-syntaxdiagram-generationuml-diagramsnon-uml-diagramsc4-model

SKILL.md Content

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PlantUML Syntax Reference

Overview

PlantUML is a Java-based tool that creates diagrams from text descriptions. It supports comprehensive UML diagrams and many non-UML diagram types.
Key advantages:
  • Most comprehensive diagram support (15+ types)
  • Mature C4 model integration with icons/sprites
  • Extensive customization options
  • Battle-tested (since 2009)
Requirements:
  • Java Runtime Environment (JRE)
  • GraphViz (for some diagram types)
  • Or use Docker: 
    docker run -p 8080:8080 plantuml/plantuml-server

Diagram Types Quick Reference

UML Diagrams

TypeKeywordsBest For
Sequence
@startuml
Interactions, API flows, protocols
Use Case
@startuml
Requirements, user stories
Class
@startuml
OOP design, domain models
Activity
@startuml
Workflows, processes
Component
@startuml
System structure
Deployment
@startuml
Infrastructure, deployment
State
@startuml
State machines

Non-UML Diagrams

TypeKeywordsBest For
JSON
@startjson
JSON structure visualization
YAML
@startyaml
YAML structure visualization
Wireframe
@startsalt
UI mockups
Gantt
@startgantt
Project timelines
MindMap
@startmindmap
Hierarchical ideas
WBS
@startwbs
Work breakdown
ER
@startuml
Database schemas
C4
@startuml
with C4 include		Software architecture

Basic Syntax

All PlantUML diagrams are wrapped in start/end tags:
plantuml
@startuml
' Your diagram code here
@enduml
Comments:
  • Single line: 
    ' This is a comment
  • Block: 
    /' This is a block comment '/
Title and captions:
plantuml
@startuml
title My Diagram Title
caption This is a caption
header Page Header
footer Page Footer

' Diagram content
@enduml

Quick Reference Card

Sequence

plantuml
@startuml
participant A
participant B
A -> B: Message
A <-- B: Response
@enduml

Class

plantuml
@startuml
class Name {
    - private
    + public
    + method()
}
A <|-- B : extends
A *-- B : contains
@enduml

Activity

plantuml
@startuml
start
:Action;
if (condition?) then (yes)
    :True path;
else (no)
    :False path;
endif
stop
@enduml

State

plantuml
@startuml
[*] --> State1
State1 --> State2 : event
State2 --> [*]
@enduml

Component

plantuml
@startuml
[Component1] --> [Component2]
database DB
Component2 --> DB
@enduml

References

For detailed syntax and complete examples, see:
ReferenceContentWhen to Load
sequence.mdParticipants, arrows, activation, groups, notesCreating sequence diagrams
class.mdClasses, visibility, relationships, cardinalityCreating class diagrams
activity.mdConditions, swimlanes, fork/joinCreating activity diagrams
state-component.mdState machines, components, deploymentCreating state/component diagrams
c4.mdC4 context, container, component diagramsCreating C4 architecture diagrams
special-diagrams.mdER, JSON, MindMap, GanttCreating non-UML diagrams
styling-setup.mdSkinparams, themes, installationCustomizing diagrams, setting up PlantUML

File Extensions

ExtensionDescription
.puml
Standard PlantUML file
.plantuml
Alternative extension
.pu
Short extension
.iuml
Include file

Test Scenarios

Scenario 1: Creating a sequence diagram

Query: "Create a PlantUML sequence diagram for user authentication"
Expected: Skill activates, provides sequence syntax with participants, arrows, and alt/else blocks

Scenario 2: Creating a class diagram

Query: "Generate a PlantUML class diagram for an e-commerce domain"
Expected: Skill activates, provides class syntax with relationships and cardinality

Scenario 3: Creating a C4 diagram

Query: "Create a C4 container diagram in PlantUML"
Expected: Skill activates, directs to c4.md reference for includes and syntax
Last Updated: 2025-12-28 PlantUML Version: 1.2024.6

Version History

  • v1.1.0 (2025-12-28): Refactored to progressive disclosure - extracted content to references/
  • v1.0.0 (2025-12-26): Initial release