PlantUML Claude Skill

A comprehensive Claude Code skill for generating PlantUML diagrams from text descriptions, converting source code to architecture diagrams, and processing markdown files. This skill supports all 19 PlantUML diagram types with enhanced features for real-world development workflows.

Installing with Skilz

Install this skill using the Skilz universal installer:

skilz install SpillwaveSolutions_plantuml/plantuml

Or install directly from GitHub:

skilz install https://github.com/SpillwaveSolutions/plantuml

Browse and explore this skill on the Skilz marketplace: View on Skilz Marketplace

Features

• Generate diagrams from natural language - Describe what you want, get PlantUML syntax
• Convert source code to diagrams - Spring Boot, FastAPI, Python ETL, Node.js, React examples
• Convert .puml files to images - Generate PNG or SVG from standalone PlantUML files
• Extract diagrams from markdown - Process both embedded puml blocks AND linked .puml files
• Unicode symbol enrichment - Add semantic meaning with security, data, and system symbols
• Validate PlantUML syntax - CI/CD-ready validation without conversion
• IDE-friendly workflow - Link to .puml files for IDE preview, convert for publication
• Confluence-ready output - Convert PlantUML to images for doc systems without native support
• Comprehensive diagram support - All UML (sequence, class, activity, state, etc.) and non-UML types (ER, Gantt, mindmap, etc.)
• Modern styling - CSS-like <style> syntax for professional diagram appearance

Quick Start

1. Verify Setup

Check that Java, Graphviz, and plantuml.jar are installed:

python scripts/check_setup.py

2. Convert a PlantUML File

# Convert to PNG
python scripts/convert_puml.py my_diagram.puml

# Convert to SVG
python scripts/convert_puml.py my_diagram.puml --format svg --output-dir images/

3. Process Markdown with PlantUML

# Process both embedded puml blocks AND linked ![](diagram.puml) files
python scripts/process_markdown_puml.py article.md

# Validate syntax without converting (great for CI/CD)
python scripts/process_markdown_puml.py article.md --validate

# Convert to SVG format
python scripts/process_markdown_puml.py article.md --format svg

Requirements

Prerequisites

1. Java (JRE 8 or higher)

   • Download from Oracle
   • Verify: java -version

2. plantuml.jar

   • Download from PlantUML
   • Place in one of these locations:
     • ~/plantuml.jar
     • /usr/local/bin/plantuml.jar
     • Or set PLANTUML_JAR environment variable

3. Graphviz (recommended, required for most UML diagrams)

   • Download from Graphviz
   • Add dot executable to PATH

Quick Setup

# macOS (with Homebrew)
brew install java graphviz
curl -o ~/plantuml.jar https://downloads.sourceforge.net/project/plantuml/plantuml.jar

# Ubuntu/Debian
sudo apt install default-jre graphviz
wget -O ~/plantuml.jar https://downloads.sourceforge.net/project/plantuml/plantuml.jar

# Verify installation
python scripts/check_setup.py

Code-to-Diagram Examples

Convert real-world application architectures to PlantUML diagrams with comprehensive examples in examples/:

Each example includes deployment, component, and sequence diagrams with production-ready patterns.

Unicode Symbol Enrichment

Enhance diagrams with semantic Unicode symbols (see references/unicode_symbols.md):

node "AWS Cloud" as aws
component "Security Service" as security
database "PostgreSQL" as db
queue "RabbitMQ" as mq
component "FastAPI App" as api

Symbol categories: Web, Data, Security, System, Messaging, Languages, Cloud, Processing, Monitoring

Linked .puml Files Support

Reference external .puml files in markdown for IDE-friendly workflows:

## Architecture

![Deployment](diagrams/deployment.puml)
![Components](diagrams/components.puml)

Benefits:

• IDEs with PlantUML support render diagrams in preview
• Version control tracks diagram changes separately
• Reuse diagrams across multiple markdown files
• Better code reviews (diff .puml files directly)
• Same script converts both embedded and linked diagrams

Usage Examples

Example 1: Create a Sequence Diagram

Create auth_flow.puml:

@startuml
participant User
participant App
participant AuthServer

User -> App: Login Request
activate App
App -> AuthServer: Validate Credentials
activate AuthServer
AuthServer --> App: Token
deactivate AuthServer
App --> User: Success
deactivate App
@enduml

Convert to image:

python scripts/convert_puml.py auth_flow.puml --format svg

Example 2: Create an ER Diagram

Create blog_schema.puml:

@startuml
entity "User" {
  *id: int
  username: string
  email: string
  created_at: datetime
}

entity "Post" {
  *id: int
  user_id: int
  title: string
  content: text
  published_at: datetime
}

entity "Comment" {
  *id: int
  post_id: int
  user_id: int
  content: text
  created_at: datetime
}

User ||--o{ Post : writes
User ||--o{ Comment : writes
Post ||--o{ Comment : has
@enduml

Example 3: Process Markdown with Multiple Diagrams

Create article.md:

# System Architecture

## Authentication Flow

```puml
@startuml
Alice -> Bob: Authentication Request
Bob --> Alice: Authentication Response
@enduml
```

## Database Schema

```puml
@startuml
entity "User" {
  *id: int
  name: string
}
entity "Order" {
  *id: int
  user_id: int
}
User ||--o{ Order
@enduml
```

Process the file:

python scripts/extract_and_convert_puml.py article.md --format png

This creates:

• article_with_images.md - Updated markdown with image links
• images/diagram_1_uml.png - First diagram
• images/diagram_2_uml.png - Second diagram

Supported Diagram Types

UML Diagrams

Non-UML Diagrams

Scripts Reference

check_setup.py

Validates PlantUML environment setup.

python scripts/check_setup.py

Checks:

• Java installation and version
• Graphviz availability
• plantuml.jar location
• Runs test diagram conversion

convert_puml.py

Converts standalone .puml files to images.

python scripts/convert_puml.py <file.puml> [options]

Options:
  --format png|svg       Output format (default: png)
  --output-dir <path>    Directory for output images (default: same as input)

process_markdown_puml.py

Enhanced markdown processor supporting both embedded code blocks AND linked .puml files.

python scripts/process_markdown_puml.py <file.md> [options]

Options:
  --format png|svg       Output format (default: png)
  --output-dir <path>    Directory for images (default: images/)
  --validate             Validate syntax without converting (CI/CD mode)

Key advantages:

• Supports IDE-friendly workflow (link to external .puml files)
• Validates syntax before conversion
• CI/CD ready with --validate flag
• Processes both embedded and linked diagrams in single pass
• Better error messages with line numbers

extract_and_convert_puml.py (Legacy)

Note: Consider using process_markdown_puml.py for enhanced features.

Extracts PlantUML diagrams from markdown and converts to images.

python scripts/extract_and_convert_puml.py <file.md> [options]

Options:
  --format png|svg       Output format (default: png)
  --output-dir <path>    Directory for images (default: images/)

Advanced Usage

Direct PlantUML Commands

# Basic PNG conversion
java -jar ~/plantuml.jar diagram.puml

# SVG output
java -jar ~/plantuml.jar --svg diagram.puml

# Batch convert all .puml files
java -jar ~/plantuml.jar "**/*.puml" --svg --output-dir images/

# Check syntax without converting
java -jar ~/plantuml.jar --check-syntax diagram.puml

# Pipe input
echo "@startuml Alice->Bob @enduml" | java -jar ~/plantuml.jar -pipe --svg > output.svg

Modern Styling

Use CSS-like <style> syntax for professional appearance:

@startuml
<style>
classDiagram {
  class {
    BackgroundColor LightBlue
    BorderColor Navy
    FontColor DarkBlue
    FontSize 14
  }
  arrow {
    LineColor SeaGreen
    LineThickness 2
  }
}
</style>

class Animal {
  -name: String
  +move()
}
class Dog extends Animal {
  +bark()
}
Animal <|-- Dog
@enduml

Themes

Quick styling with built-in themes:

@startuml
!theme cerulean

' Your diagram content
@enduml

Available themes: cerulean, bluegray, plain, sketchy, amiga

Documentation

The references/ directory contains comprehensive guides:

Core References

• toc.md - Navigation hub for all diagram types
• plantuml_reference.md - Installation, CLI, troubleshooting
• common_format.md - Universal syntax elements
• styling_guide.md - Modern <style> syntax guide
• unicode_symbols.md - Complete Unicode symbol guide for semantic enrichment

Diagram Type Guides

• sequence_diagrams.md
• class_diagrams.md
• And more for each diagram type...

Code Examples

Troubleshooting

"plantuml.jar not found"

• Download from https://plantuml.com/download
• Place in ~/plantuml.jar or set PLANTUML_JAR environment variable
• Verify: python scripts/check_setup.py

"Graphviz not found"

• Install from https://graphviz.org/download/
• Add dot executable to PATH
• Some diagrams (JSON, YAML, Gantt, MindMap) don't require Graphviz

"Syntax Error?"

• Verify @start/@end delimiters match
• Check diagram-specific syntax in references/[diagram_type].md
• Use java -jar plantuml.jar --check-syntax file.puml

"Java not found"

• Install Java JRE/JDK 8+
• Add to PATH
• Verify: java -version

Tips and Best Practices

1. Use descriptive filenames - user_auth_sequence.puml instead of diagram1.puml
2. Add comments - Use ' for single-line comments to document complex logic
3. Choose SVG for documentation - Scalable, better quality, supports hyperlinks
4. Use PNG for web - Smaller file sizes, fixed resolution
5. Start simple - Test basic diagrams before adding complexity
6. Version control - Commit .puml source files to Git
7. Prefer modern styling - Use <style> tags instead of legacy skinparam

Use with Claude Code

This is a Claude Code skill. When loaded, Claude can:

• Generate PlantUML syntax from natural language descriptions
• Select the appropriate diagram type for your use case
• Create properly formatted .puml files
• Convert diagrams to images
• Extract and process diagrams from markdown files
• Apply modern styling for professional appearance

Simply describe what you want: "Create a sequence diagram for user authentication" or "Extract all diagrams from my article.md and convert to SVG".

Resources

• PlantUML Official Site
• PlantUML Language Reference Guide (PDF)
• PlantUML GitHub
• Graphviz Downloads

License

This skill is provided as-is for use with Claude Code.