Plantuml Skill

This is a zero-install diagramming tool that uses PlantUML syntax and renders through the Kroki cloud API, so you just need curl. It handles sequence diagrams, component architecture, class models, ER schemas, and about a dozen other UML types. The skill knows to activate proactively when you're explaining systems with multiple moving parts, which is actually useful instead of waiting to be asked. The syntax reference is thorough and includes real color codes and arrow types. If you're offline or don't trust the cloud, it falls back to local Kroki Docker or a traditional PlantUML jar setup. Much faster than fighting with Graphviz installation issues.

skills.sh installs: 4.1K
GitHub stars: 100
last updated: Aug 21, 2026

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Install

$ npx -y skills add agents365-ai/365-skills --skill plantuml-skill --agent claude-code

Installs into .claude/skills of the current project.

Files

PlantUML Diagram Skill

Overview

Generate .puml PlantUML diagram files and export to PNG/SVG using Kroki — a cloud rendering API that requires no local installation beyond curl.

Format: .puml (PlantUML text) Renderer: Kroki API (https://kroki.io) — just curl, no Java needed Output: PNG, SVG Diagram types: sequence, component, class, ER, activity, use case, state, C4, and more

When to Use

Explicit triggers:

"plantuml diagram", "sequence diagram", "class diagram", "component diagram"
"UML", "activity diagram", "use case diagram", "state machine"
"visualize", "draw", "diagram", "flowchart", "architecture chart"

Proactive triggers:

Explaining a system with 3+ interacting components
Describing API flows, authentication sequences, message passing
Showing class hierarchies, database schemas, or ER models
Illustrating state machines or lifecycle flows

When NOT to use it — route elsewhere:

General, non-UML quick diagrams embedded in Markdown → mermaid.
Freeform, heavily-styled, or branded diagrams needing pixel control → drawio.
A hand-drawn / sketchy look → excalidraw or tldraw.