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
| Type | Keywords | Best 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
| Type | Keywords | Best 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:
@startuml
' Your diagram code here
@endumlComments:
- Single line:
' This is a comment - Block:
/' This is a block comment '/
Title and captions:
@startuml
title My Diagram Title
caption This is a caption
header Page Header
footer Page Footer
' Diagram content
@endumlQuick Reference Card
Sequence
@startuml
participant A
participant B
A -> B: Message
A <-- B: Response
@endumlClass
@startuml
class Name {
- private
+ public
+ method()
}
A <|-- B : extends
A *-- B : contains
@endumlActivity
@startuml
start
:Action;
if (condition?) then (yes)
:True path;
else (no)
:False path;
endif
stop
@endumlState
@startuml
[*] --> State1
State1 --> State2 : event
State2 --> [*]
@endumlComponent
@startuml
[Component1] --> [Component2]
database DB
Component2 --> DB
@endumlReferences
For detailed syntax and complete examples, see:
| Reference | Content | When to Load |
|---|---|---|
| sequence.md | Participants, arrows, activation, groups, notes | Creating sequence diagrams |
| class.md | Classes, visibility, relationships, cardinality | Creating class diagrams |
| activity.md | Conditions, swimlanes, fork/join | Creating activity diagrams |
| state-component.md | State machines, components, deployment | Creating state/component diagrams |
| c4.md | C4 context, container, component diagrams | Creating C4 architecture diagrams |
| special-diagrams.md | ER, JSON, MindMap, Gantt | Creating non-UML diagrams |
| styling-setup.md | Skinparams, themes, installation | Customizing diagrams, setting up PlantUML |
File Extensions
| Extension | Description |
|---|---|
.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