Bee Tools' free online PlantUML editor. Draw flowcharts, sequence diagrams, use case diagrams, class diagrams, state diagrams and component diagrams from text, with live preview and one-click SVG / high-res PNG export. Configurable render server.
Draw professional UML diagrams from text, with live preview. PlantUML lets you describe UML and architecture diagrams in a concise declarative syntax; the preview renders on the right as a crisp vector image. It uses a public PlantUML render server by default, or you can enter your own self-hosted / private server URL above. Content is edited locally and rendered on demand.
PlantUML syntax cheat sheet
What is PlantUML
PlantUML, created by Arnaud Roques, is an open-source textual language for generating diagrams. Compared with drag-and-drop drawing, text lets you version diagrams and generate them in bulk.
Common diagrams
@startuml / @enduml —— every diagram must be wrapped in this pair.
Activity —— :step; denotes an activity; if (cond) then (yes) ... else (no) ... endif is a branch; start/stop mark begin/end.
Sequence —— actor defines a participant; A -> B: msg is a message; --> is a reply; activate/deactivate control lifelines.
Use case —— usecase "Name" as UC, actor --> UC is an association, <.. is include/generalization.
Class —— class Animal { +String name +eat() }, Animal <|-- Dog is inheritance, : +bark() is a method.
State —— [*] --> State, State --> [*] are start/end, State --> Other : trigger is a transition.
Component —— group with package, [A] --> [B] is a dependency.
Tips
Use title and legend to improve readability.
Partition complex diagrams with package / rectangle to reduce crossings.
Tune colors, fonts and rounding with skinparam.
Edit the sample on the left and watch the live preview on the right.
Frequently asked questions
What is PlantUML?
PlantUML is an open-source tool that generates UML and many other diagram types from a simple textual description: flowcharts, sequence diagrams, use case, class, state, component, deployment diagrams and more.
Are diagrams saved or uploaded?
The editor content is kept in your browser's local cache (survives refresh), but rendering requires sending the text to the configured render server. With the default public server, diagram text is sent to plantuml.com.
Can I use a private / self-hosted server?
Yes. Enter your own PlantUML server root URL (e.g. https://your-host/plantuml) in 'Render server URL'. Export and copy require that server to allow cross-origin (CORS) requests.
Which diagram types are supported?
All PlantUML types: activity, sequence, use case, class, object, state, component, deployment, timing, Gantt, mindmap and more.
Will SVG / PNG export lose quality?
SVG is a vector format and never blurs. PNG is produced by the render server at the chosen factor (1x–4x), suitable for most documents.