How to use it
- Pick the closest template or paste existing PlantUML.
- Edit the text; the preview updates about a second later, and errors are marked in the image.
- Download SVG for documents and web pages or PNG to share; a share link sends the diagram with its source for others to edit.
Supported diagram types
| Starts with | Diagrams |
|---|---|
@startuml … @enduml | Sequence, use case, class, activity, component, state, deployment, ER |
@startgantt | Gantt charts (project plans) |
@startmindmap | Mind maps |
@startwbs | Work breakdown structures |
@startjson / @startyaml | JSON and YAML structures |
@startsalt | UI wireframes |
nwdiag { … } | Network diagrams |
!include <C4/C4_Container> | C4 architecture (bundled library) |
Syntax cheat sheet
| Syntax | Meaning |
|---|---|
A -> B : message | Solid arrow (call) |
A --> B | Dashed arrow (reply) |
alt / else / end | Alternatives |
loop … end | Loop |
:step; | An activity step |
if (paid?) then (yes) | Activity decision |
|Sales| | Swimlane |
note right: text | Note |
skinparam monochrome true | Black and white for printing |
' comment | Comment line (starts with a quote) |
Frequently asked questions
What is PlantUML?
PlantUML is an open-source tool that draws diagrams from plain text: one line such as "Buyer → Sales : RFQ" becomes a sequence message. Text lives in Git, docs and tickets, is faster to edit than drag-and-drop, and diffs cleanly.
Are my diagrams stored or published?
No. For the preview the source is sent to this site's server, rendered and discarded, never stored or logged; PlantUML runs in sandbox mode with no file or network access. Share links carry the compressed source inside the link, visible only to people you send it to.
Why do Chinese text and PNG exports look right?
The preview and SVG use your browser's fonts, and PNG is drawn in the browser from the SVG at 2× resolution, so Chinese, Japanese and other scripts never turn into boxes.
Can I !include external files?
For security, local files and URLs cannot be included; the bundled standard library works, such as the C4 library (C4/C4_Container) and icon sets like AWS.