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Add PlantUML diagrams

Use PlantUML when you need sequence, component, or deployment diagrams that are easier to maintain as text than as static images.

Mermaid is built in

For flowcharts, sequence diagrams, and state machines, Mermaid renders natively in Docusaurus without an external service. Use PlantUML when you need diagram types that Mermaid does not support.

Live example​

The following PlantUML block renders as an SVG image at build time:

Search index flow

Prerequisites​

  • Your docs page uses Markdown or MDX.
  • The page is in a docset that uses the remarkPlantuml plugin.
  • Readers can load images from the configured PlantUML rendering endpoint.

1. Add a fenced block​

Add a fenced code block with plantuml as the language:

```plantuml Component diagram
@startuml
skinparam componentStyle rectangle
skinparam backgroundColor transparent

[Docusaurus site] --> [Search index builder]
[Search index builder] --> [Algolia]
@enduml
```

The text after plantuml becomes the image alt text. Use short, descriptive text that explains the diagram purpose.

2. Keep diagrams close to the explanation​

Place the diagram near the section that explains it. Follow the diagram with the main takeaway in prose so readers do not need to interpret the image alone.

3. Verify rendering​

Build the site:

npm run build

Open the generated page or run the dev server:

npm start

Confirm that the diagram loads as an SVG image and that the alt text describes the diagram.

Rendering behavior​

DevDocify converts plantuml fences into image links during Markdown processing. The plugin encodes the diagram source and points the image to the configured PlantUML SVG endpoint.

By default, rendering uses https://www.plantuml.com/plantuml/svg. If you need self-hosted rendering, update PLANTUML_BASE_URL in src/remark/remark-plantuml.ts and rebuild.

Troubleshooting​

  • Diagram does not appear: confirm the page uses a docset configured with remarkPlantuml.
  • Image request fails: confirm the rendering endpoint is reachable from the browser.
  • Alt text is too generic: add concise text after plantuml in the opening fence.

Mermaid diagrams (built in)​

Mermaid renders natively in Docusaurus without an external service. Use it for flowcharts, sequence diagrams, state machines, and entity relationship diagrams.

Add a Mermaid diagram using a mermaid fenced block. No plugin or external endpoint is needed.