Sirena vs Other Diagram Tools
Purpose
This page compares Sirena with other popular diagram generation tools to help you choose the right tool for your needs.
Overview
Sirena is a pure Ruby renderer for Mermaid syntax, for server-side use. Compatibility with Mermaid.js varies by diagram type; see the compatibility page.
Feature Comparison Matrix
| Feature | Sirena | Mermaid.js | PlantUML | Graphviz |
|---|---|---|---|---|
Language |
Ruby |
JavaScript |
Java |
C/C++ |
Diagram Types |
24 |
20+ |
Not counted here |
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 |
|
|
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 syntax (partial parity) |
Mermaid native |
PlantUML DSL |
DOT language |
Rails Integration |
None built-in; call |
Via Node bridge |
Via Java bridge |
Limited |
Documentation |
AsciiDoc/Jekyll |
Markdown |
AsciiDoc |
Man pages |
Open Source |
BSD-2-Clause |
MIT |
GPL/Apache |
EPL |
Memory Usage |
Not benchmarked |
Not measured in the linked report |
Not measured in the linked report |
Not measured in the linked report |
Startup Time |
Measured in the linked dated Sirena report |
Measured in the linked dated Sirena report |
Not measured in the linked report |
Not measured in the linked report |
Detailed Comparison
Sirena (This Tool)
Strengths:
-
Pure Ruby - no Node.js or Java dependencies
-
Callable directly from Rails, Jekyll, and other Ruby applications (no dedicated integration layer built yet)
-
A dated Apple M2 run against mermaid-cli is published with reproduction commands and scope limits (see Performance Benchmarks below)
-
YAML-based theme system
-
Reads Mermaid.js syntax (partial parity)
-
Built-in batch processor
-
Runs in any Ruby CI job
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
-
Simpler deployment (no Node.js/Java runtime dependency)
Mermaid.js
Strengths:
-
Large, active community
-
Browser-based rendering (client-side)
-
Interactive diagrams with click events
-
Live editor (mermaid.live)
-
20+ diagram types
-
JavaScript ecosystem integration
Limitations:
-
Requires Node.js for CLI
-
Requires Puppeteer/Chrome for server rendering
-
Server-rendering memory was not measured in the linked report
-
Startup was measured only in the linked, single-machine report
-
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)
-
Multiple output formats
-
Java ecosystem integration
-
Server mode available
Limitations:
-
Requires Java JRE
-
PlantUML-specific syntax (not Mermaid)
-
More complex installation
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
-
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
The benchmark:compare and benchmark:quick rake tasks run against
Sirena.render. One dated Apple M2 comparison with mermaid-cli, its method,
and reproduction commands is published in the
Performance Benchmark report. That report did
not measure memory, and one machine’s result is not a general performance
guarantee or a comparison with PlantUML or Graphviz.
Migration Paths
From Mermaid.js to Sirena
Syntax Compatibility: partial; see the compatibility page and scoreboard/corpus.json
Migration Steps:
-
Replace
npm install mermaidwithgem install sirena -
Change rendering calls from JavaScript to Ruby
-
Adapt themes from CSS to YAML
-
Remove click event handlers (not supported)
-
Test batch rendering against your own workload (the single published run does not substitute for this)
A migration guide is planned.
From PlantUML to Sirena
Syntax Compatibility: Sirena renders PlantUML class and sequence diagrams when started with --require sirena/notation/plantuml (scoreboard/plantuml.json: class 35/35, sequence 77/77 oracle-valid cases). Other PlantUML diagram types are not supported.
Migration Strategy:
-
Identify diagram types needed
-
Load the PlantUML notation for class and sequence diagrams; rewrite other PlantUML syntax to Mermaid syntax
-
Test rendering with Sirena
-
Adapt theming and styling
-
Update build scripts
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 (no Node.js/Java runtime)
✅ 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
Hybrid Approaches
Ecosystem Comparison
| Tool | Framework Integration | Build Tool Support |
|---|---|---|
Sirena |
Callable from any Ruby framework (Rails, Jekyll, Sinatra, Padrino) via |
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 |
BSD-2-Clause |
✅ 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
Conclusion
Each tool has its strengths and ideal use cases:
-
Sirena renders Mermaid syntax server-side in Ruby
-
Mermaid.js renders interactive browser-based diagrams
-
PlantUML targets UML documentation
-
Graphviz is a general graph layout tool
Choose based on your tech stack, rendering requirements, and diagram complexity. For Ruby applications needing server-side Mermaid-compatible rendering without a Node.js or Java runtime, Sirena may fit; see "Performance Benchmarks" above for the scoped measurement and its limits.