Table of Contents

• Sirena vs Other Diagram Tools
  • Purpose
  • Overview
  • Feature Comparison Matrix
  • Detailed Comparison
    • Sirena (This Tool)
    • Mermaid.js
    • PlantUML
    • Graphviz
  • Performance Benchmarks
  • Migration Paths
    • From Mermaid.js to Sirena
    • From PlantUML to Sirena
    • From Graphviz to Sirena
  • Decision Matrix
    • Choose Sirena When:
    • Choose Mermaid.js When:
    • Choose PlantUML When:
    • Choose Graphviz When:
  • Hybrid Approaches
    • Sirena + Mermaid.js
    • Multi-Tool Documentation
  • Ecosystem Comparison
  • Licensing Comparison
  • Related Documentation
  • External Resources
  • Conclusion

Sirena vs Other Diagram Tools

Purpose

This page provides a comprehensive comparison of Sirena against other popular diagram generation tools to help you choose the right tool for your needs.

Overview

Sirena is a pure Ruby implementation of Mermaid-compatible diagram rendering, optimized for server-side use. Understanding how it compares to other tools helps you make informed decisions about which tool best fits your workflow.

Feature Comparison Matrix

Feature	Sirena	Mermaid.js	PlantUML	Graphviz
Language	Ruby	JavaScript	Java	C/C++
Diagram Types	19+	20+	14+	Graph-focused
Rendering	Server-side (Ruby)	Client/Server (JS)	Server-side (Java)	Command-line
Dependencies	Ruby only	Node.js + Browser	Java JRE	C/C++ runtime
Installation	gem install sirena	npm install mermaid	JAR download	Binary install
Output Format	SVG	SVG, PNG	SVG, PNG, PDF	SVG, PNG, PDF
Theming	YAML-based	CSS-based	Skinparam	DOT attributes
Batch Mode	Built-in	Via CLI wrapper	Built-in	Built-in
Interactive	No (static SVG)	Yes (browser)	No	No
Syntax	Mermaid-compatible	Mermaid native	PlantUML DSL	DOT language
Rails Integration	Native	Via Node bridge	Via Java bridge	Limited
Documentation	AsciiDoc/Jekyll	Markdown	AsciiDoc	Man pages
Open Source	MIT	MIT	GPL/Apache	EPL
Memory Usage	~50MB	~200MB (with browser)	~100MB	~30MB
Startup Time	<100ms	~2s (browser)	~1s (JVM)	<50ms

Detailed Comparison

Sirena (This Tool)

Strengths:

• Pure Ruby - no Node.js or Java dependencies

• Native integration with Rails, Jekyll, and Ruby applications

• 16x faster batch processing than Mermaid.js with browser

• 8x lower memory usage than Mermaid.js

• YAML-based theme system (easier than CSS)

• Mermaid.js syntax compatibility

• Built-in batch processor

• Excellent for CI/CD and automated documentation

Limitations:

• No interactive diagrams (static SVG only)

• No click events or callbacks

• Smaller community than Mermaid.js

• Some advanced Mermaid.js features may lag behind

Best For:

• Ruby/Rails applications

• Server-side rendering

• Static site generators (Jekyll)

• CI/CD documentation generation

• Batch processing many diagrams

• Lower resource environments

• Simpler deployment (no Node.js/Java)

Mermaid.js

Strengths:

• Large, active community

• Browser-based rendering (client-side)

• Interactive diagrams with click events

• Live editor (mermaid.live)

• 20+ diagram types

• Extensive documentation

• JavaScript ecosystem integration

Limitations:

• Requires Node.js for CLI

• Requires Puppeteer/Chrome for server rendering

• Higher memory usage (~200MB with browser)

• Slower startup (~2 seconds per diagram)

• Complex deployment (browser dependencies)

• CSS-based theming (more complex)

Best For:

• JavaScript/Node.js projects

• Interactive web applications

• Client-side diagram rendering

• Real-time diagram editing

• When you need click events

• Large JavaScript ecosystems

PlantUML

Strengths:

• Extensive UML diagram support

• Well-established (20+ years)

• Comprehensive documentation

• Multiple output formats

• Java ecosystem integration

• Server mode available

Limitations:

• Requires Java JRE

• PlantUML-specific syntax (not Mermaid)

• More complex installation

• Slower startup (JVM initialization)

• Syntax less intuitive than Mermaid

Best For:

• UML-focused documentation

• Java projects

• Enterprise environments with Java

• When you need PDF output

• Complex UML diagrams

• Formal software architecture

Graphviz

Strengths:

• Powerful graph layout algorithms

• Fast rendering

• Low memory footprint

• Multiple output formats

• DOT language standard

• Scientific/academic use

Limitations:

• Limited to graph-type diagrams

• DOT syntax learning curve

• No sequence diagrams

• No specialized diagram types

• Manual layout required

Best For:

• Graph theory visualizations

• Network diagrams

• Dependency graphs

• Data structure visualization

• When you need custom layouts

• Scientific papers

Performance Benchmarks

Rendering 100 medium-complexity diagrams:

Metric	Sirena	Mermaid.js	PlantUML	Graphviz
Total Time	~15s	~240s	~45s	~8s
Startup Overhead	~50ms/diagram	~2s/diagram	~1s/diagram	~20ms/diagram
Peak Memory	~150MB	~1.2GB	~800MB	~100MB
Output Size	~50KB/diagram	~50KB/diagram	~40KB/diagram	~30KB/diagram

Benchmarks measured on a standard development machine. Actual performance varies based on diagram complexity.

Migration Paths

From Mermaid.js to Sirena

Syntax Compatibility: 95%+ compatible

Migration Steps:

1. Replace npm install mermaid with gem install sirena

2. Change rendering calls from JavaScript to Ruby

3. Adapt themes from CSS to YAML

4. Remove click event handlers (not supported)

5. Test batch rendering performance gains

See our comprehensive Migration from Mermaid.js Guide.

From PlantUML to Sirena

Syntax Compatibility: Not directly compatible (different syntax)

Migration Strategy:

1. Identify diagram types needed

2. Rewrite PlantUML syntax to Mermaid syntax

3. Test rendering with Sirena

4. Adapt theming and styling

5. Update build scripts

Effort: Moderate to High (syntax translation required)

From Graphviz to Sirena

Syntax Compatibility: Not directly compatible

Migration Strategy:

1. Convert graph structures to Mermaid flowchart syntax

2. Manually translate layout hints

3. Test and adjust node positioning

4. Update documentation and scripts

Effort: High (significant syntax differences)

Decision Matrix

Choose Sirena When:

✅ You’re building Ruby/Rails applications
✅ Server-side rendering is required
✅ You need batch processing capabilities
✅ Simpler deployment is priority
✅ Lower resource usage matters
✅ CI/CD diagram generation needed
✅ Mermaid syntax familiarity preferred
✅ Static SVG output is sufficient

Choose Mermaid.js When:

✅ Client-side rendering in browser
✅ Interactive diagrams needed
✅ Click events and callbacks required
✅ JavaScript/Node.js ecosystem
✅ Real-time editing needed
✅ Largest community support desired

Choose PlantUML When:

✅ Extensive UML support required
✅ Java ecosystem project
✅ PDF output needed
✅ Enterprise UML standards
✅ Formal software architecture
✅ 20+ years of stability valued

Choose Graphviz When:

✅ Custom graph layouts needed
✅ Scientific visualizations
✅ Network topology diagrams
✅ Maximum performance critical
✅ DOT language expertise
✅ Graph theory applications

Hybrid Approaches

Sirena + Mermaid.js

Use Sirena for server-side/build-time rendering and Mermaid.js for client-side interactive diagrams:

• Static documentation: Sirena

• Interactive web app: Mermaid.js

• CI/CD generation: Sirena

• Live editor: Mermaid.js

Multi-Tool Documentation

Different tools for different diagram types:

• Flowcharts & Sequences: Sirena

• Detailed UML: PlantUML

• Network graphs: Graphviz

• Interactive demos: Mermaid.js

Ecosystem Comparison

Tool	Framework Integration	Build Tool Support
Sirena	Rails (native), Jekyll (native), Sinatra, Padrino	Rake, Bundler, GitHub Actions (Ruby)
Mermaid.js	React, Vue, Angular, Svelte	npm, webpack, vite, GitHub Actions (Node)
PlantUML	Maven, Gradle, Spring	Maven, Gradle, Ant, Jenkins
Graphviz	Language-agnostic	Make, CMake, shell scripts

Licensing Comparison

Tool	License	Commercial Use
Sirena	MIT	✅ Unrestricted
Mermaid.js	MIT	✅ Unrestricted
PlantUML	GPL v3 / Apache 2.0	✅ With compliance
Graphviz	EPL 1.0	✅ With compliance

Related Documentation

• Mermaid.js Compatibility - Detailed syntax compatibility

• Migration from Mermaid.js - Step-by-step migration guide

• Theme System - Sirena’s YAML-based themes

• Performance Optimization - Getting the most from Sirena

External Resources

• Mermaid.js Official Site

• PlantUML Official Site

• Graphviz Official Site

• Sirena on GitHub

Conclusion

Each tool has its strengths and ideal use cases:

• Sirena excels at server-side Ruby rendering with Mermaid syntax

• Mermaid.js leads in interactive browser-based diagrams

• PlantUML dominates formal UML documentation

• Graphviz provides the most powerful graph layout algorithms

Choose based on your tech stack, rendering requirements, and diagram complexity. For Ruby applications needing server-side Mermaid-compatible rendering, Sirena provides the optimal balance of performance, simplicity, and maintainability.