Sirena Documentation

Welcome to Sirena, a pure Ruby Mermaid diagram rendering library that converts Mermaid syntax into beautiful SVG diagrams. Built for server-side rendering, Sirena provides native integration with Ruby applications without requiring Node.js or browser dependencies.

Why Sirena?

Pure Ruby Implementation

  • No Node.js dependencies

  • No Puppeteer/Chrome requirements

  • Simpler deployment in Ruby environments

  • Native integration with Rails, Jekyll, and Ruby applications

Better Performance

  • Faster startup (no browser launch)

  • Lower memory footprint

  • Better for batch processing

  • Suitable for serverless environments

Comprehensive Diagram Support

  • 19 diagram types fully implemented

  • Mermaid.js syntax compatibility

  • Advanced theming system

  • Professional-quality SVG output

Quick Start 

# Installation
gem install sirena

# Basic usage
require 'sirena'

svg = Sirena.render(<<~MERMAID)
  graph TD
    Start --> End
MERMAID

puts svg

See link:{% link _tutorials/getting-started.adoc %}[Getting Started Tutorial] for complete installation and usage instructions.

Documentation Structure

link:{% link _pages/index.adoc %}[Core Topics]

Essential concepts and architecture you need to understand Sirena.

link:{% link _tutorials/index.adoc %}[Tutorials]

Step-by-step guides to help you get started and accomplish specific tasks.

link:{% link _guides/index.adoc %}[Guides]

In-depth guides for advanced features and best practices.

link:{% link _diagram_types/index.adoc %}[Diagram Types]

Complete reference for all 19 diagram types with syntax and examples.

link:{% link _features/index.adoc %}[Features]

Detailed documentation of Sirena’s unique features and capabilities.

link:{% link _references/index.adoc %}[References]

Complete API and CLI references for quick lookup.

Supported Diagram Types

Sirena supports 19 diagram types compatible with Mermaid.js syntax:

Type Use Case

link:{% link _diagram_types/flowchart.adoc %}[Flowchart]

Process flows and directed graphs

link:{% link _diagram_types/sequence-diagram.adoc %}[Sequence]

Message interactions over time

link:{% link _diagram_types/class-diagram.adoc %}[Class]

Object-oriented class structures

link:{% link _diagram_types/state-diagram.adoc %}[State]

State machines and transitions

link:{% link _diagram_types/er-diagram.adoc %}[ER Diagram]

Database entity relationships

link:{% link _diagram_types/user-journey.adoc %}[User Journey]

User experience mapping

link:{% link _diagram_types/git-graph.adoc %}[Git Graph]

Repository history visualization

link:{% link _diagram_types/pie-chart.adoc %}[Pie Chart]

Proportional data visualization

link:{% link _diagram_types/gantt-chart.adoc %}[Gantt Chart]

Project timeline planning

link:{% link _diagram_types/quadrant-chart.adoc %}[Quadrant]

Priority/complexity matrices

link:{% link _diagram_types/requirement-diagram.adoc %}[Requirement]

Requirements traceability

link:{% link _diagram_types/c4-diagram.adoc %}[C4]

Software architecture (Context, Container, Component, Code)

link:{% link _diagram_types/mindmap.adoc %}[Mindmap]

Hierarchical idea organization

link:{% link _diagram_types/timeline.adoc %}[Timeline]

Historical event visualization

link:{% link _diagram_types/sankey-diagram.adoc %}[Sankey]

Flow quantity visualization

link:{% link _diagram_types/xy-chart.adoc %}[XY Chart]

Data point plotting

link:{% link _diagram_types/block-diagram.adoc %}[Block]

Component relationships

link:{% link _diagram_types/architecture-diagram.adoc %}[Architecture]

System architecture views

link:{% link _diagram_types/kanban-diagram.adoc %}[Kanban]

Workflow board visualization

See the complete link:{% link _diagram_types/index.adoc %}[Diagram Types Reference] for detailed syntax and examples.

Key Features

  • Theme System: YAML-based theming with 4 built-in themes (default, dark, light, high-contrast)

  • Batch Processing: Built-in batch renderer for documentation sets

  • Rails Integration: Native Ruby integration with Rails helpers

  • Jekyll Support: Static site generation compatibility

  • Parslet Parsing: Robust grammar-based parsing with clear error messages

  • SVG Output: Professional-quality scalable vector graphics

Compatibility & Comparison

Sirena maintains syntax compatibility with Mermaid.js while providing a pure Ruby implementation optimized for server-side rendering.

  • link:{% link _pages/compatibility.adoc %}[Mermaid.js Compatibility] - Detailed syntax compatibility matrix

  • link:{% link _pages/comparison.adoc %}[Tool Comparison] - Compare Sirena with Mermaid.js, PlantUML, and Graphviz

Getting Help

License

Sirena is open source under the MIT License.

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Copyright © 2025 Ribose. Sirena is open source under the MIT license.

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