What is the difference between Mermaid and PlantUML?

Mermaid is best for Developers wanting text-based diagrams in markdown, while PlantUML is best for Software architects who need comprehensive UML diagram support. Mermaid starts at Free and PlantUML starts at Free.

Is Mermaid or PlantUML cheaper?

Mermaid starts at Free and is free. PlantUML starts at Free and is free.

Is there a free alternative to PlantUML?

Both Mermaid and PlantUML offer free tiers.

Mermaid vs PlantUML (2026)

At a glance

	Mermaid	PlantUML
Best for	Developers wanting text-based diagrams in markdown	Software architects who need comprehensive UML diagram support
Starting price	Free	Free
Free tier	✓	✓
Open source	✓	✓
Free tier available	✓	✓
Open source	✓	✓
Git-Friendly	✓	—
IDE integration	—	✓
Many Chart Types	✓	—
Markdown	✓	—
Open source	—	✓
Text-Based	✓	—
Text-based	—	✓
UML diagrams	—	✓

Mermaid

Strengths

Open source and transparent
Includes Text-Based as a core feature, purpose-built for diagramming workflows
Fully open-source — you can self-host, audit the code, and avoid vendor lock-in
The core product is free with no paywalled essentials

Weaknesses

May lack some advanced features
Self-hosting is free but requires server maintenance and DevOps knowledge
Fewer built-in features means you may need additional tools to cover gaps
Ecosystem of third-party integrations is smaller than the market leaders in diagramming

Try Mermaid → Full review

PlantUML

Strengths

Most comprehensive UML support of any diagramming tool
Text-based format integrates with version control
Wide IDE support (VS Code, IntelliJ, Eclipse)
Active community with 15+ years of development

Weaknesses

Steep learning curve for the text syntax
Output style is functional but not aesthetically modern
Layout control is limited — auto-layout can produce awkward results
Less suitable for non-UML diagram types

Try PlantUML → Full review

The bottom line

Pricing: Both Mermaid and PlantUML are free, so this decision comes down to features and philosophy rather than budget.

Feature gaps: Mermaid offers Git-Friendly, Many Chart Types and Markdown that PlantUML lacks. PlantUML brings IDE integration, Open source and Text-based that Mermaid does not have.

Open source: Both Mermaid and PlantUML are open source, so self-hosting and code audits are on the table with either choice.

Where each tool shines: Mermaid's biggest strengths are: open source and transparent. includes text-based as a core feature, purpose-built for diagramming workflows. PlantUML's biggest strengths are: most comprehensive uml support of any diagramming tool. text-based format integrates with version control.

Watch out for: With Mermaid, users commonly note that may lack some advanced features. With PlantUML, the main complaint is that steep learning curve for the text syntax.

Choose Mermaid if...

Your profile matches its sweet spot: developers wanting text-based diagrams in markdown
You specifically need Git-Friendly and Many Chart Types
You care about includes text-based as a core feature, purpose-built for diagramming workflows

Choose PlantUML if...

You need a tool built for software architects who need comprehensive uml diagram support
You specifically need IDE integration and Open source
You care about text-based format integrates with version control