PlantUML Online Editor

How to use the PlantUML Editor

1. Open the page and type or paste your PlantUML between @startuml and @enduml.
2. To work on an existing file, open a .puml, .plantuml, .pu, .iuml or .txt file instead.
3. Keep typing. The diagram redraws as you go, so a syntax problem shows up in the preview right away.
4. Check the preview panel and the notes listed under the diagram for what was skipped.
5. Click the Edit button under the text. It names the matching tool, such as Edit in the Sequence Diagram Maker, and opens the diagram there to change by hand. This is free.
6. Download the result as a PNG at 1x, 2x or 4x, as an SVG, or as a picture PDF. None of these carry a watermark.
7. Use the Examples menu to load a working sequence, class, entity, state or activity sample when you want to see the syntax this editor reads, then change it line by line.

Your work autosaves in this browser, and the Saved menu keeps named copies. To share a diagram, create a share link from the Saved menu. The link itself holds the document, so the person you send it to does not need an account and nothing is stored on a server.

What is a PlantUML online editor?

A PlantUML online editor is a browser-based workspace for writing PlantUML text, previewing the diagram it describes, and exporting the picture. You do not need a local PlantUML installation, Java, or a server of your own. This editor follows that model: you type between @startuml and @enduml, and the drawing updates as you go.

PlantUML is a text language. Lines between the start and end markers describe participants, classes, states or steps. Because the source is plain text, you can keep it in version control, paste it into a chat, or change one word and see the effect straight away.

This editor is a reader written for this site, not the PlantUML Java program. It covers common syntax, but styling such as skinparam, colours and notes on classes is left out. Most of what is skipped is listed under the diagram, so you can see what did not carry over; box titles and stereotypes on participants are dropped without a note. If a file holds several @startuml blocks, the first is drawn and a note says so. The old activity syntax with (*) is refused with a message.

Which PlantUML diagram types can I edit here?

You can edit sequence, class, entity (ER), state, activity, use case, component, mind map (@startmindmap) and Gantt (@startgantt) diagrams here. Node, database and cloud shapes from deployment diagrams are read as components. Timing diagrams are refused with a message. Each supported type opens in its matching tool with the Edit button.

Each diagram is drawn by this site’s own tool for its type, so spacing and arrow placement may differ from PlantUML’s output.

What this does not do

• It is not the PlantUML Java program, so spacing and arrows differ from PlantUML’s own output.
• It leaves out styling such as skinparam, colours and notes on classes. Most of what is skipped is listed under the diagram; box titles and stereotypes on participants are dropped without a note.
• It draws only the first @startuml block of a file, with a note.
• It refuses timing diagrams and the old activity syntax with (*), and reads deployment shapes as components.

Frequently asked questions

• 

  Mermaid to draw.io Converter

  use it when your diagram source is written in Mermaid rather than PlantUML.
• 

  Code to Flowchart

  use it to turn code into a flowchart of its logic.
• 

  Sequence Diagram Maker

  use it when you want to draw or hand-edit message flows between participants.
• 

  UML Class Diagram Maker

  use it to adjust class boxes and relationships after a PlantUML class diagram renders.
• 

  State Diagram Maker

  use it to refine state machines you started in PlantUML.
• 

  Use Case Diagram Maker

  use it to edit actors and use cases by hand.