PlantUML: Text-Based UML Diagramming 10x Faster Than Visio

What Is PlantUML

PlantUML is an open-source project that enables rapid diagramming through a textual description language. It defines a complete language for describing UML relationships and uses the Graphviz rendering library to generate diagrams, which can be exported as images or SVG vector files.

Advantages of PlantUML

Pure text-based editing — no drag-and-drop, automatic layout adjustment, simple and clean.

Platform-independent — runs anywhere with the PlantUML JAR, no platform lock-in.

Integrates with multiple editors and IDEs such as IntelliJ IDEA, Eclipse, and Notepad++.

Installing the PlantUML Plugin in IntelliJ IDEA

Open File → Settings → Plugins, search for PlantUML , and install PlantUML integration .

Installing Graphviz

PlantUML relies on Graphviz for rendering. Download the Windows installer from:

https://graphviz.gitlab.io/_pages/Download/windows/graphviz-2.38.msi

After installation, configure environment variables:

Add GRAPHVIZ_HOME with the installation path (e.g., D:\WorkWare\Graphviz2.38).

Append %GRAPHVIZ_HOME%\bin to the Path variable (separate entries with semicolons).

Add GRAPHVIZ_DOT pointing to %GRAPHVIZ_HOME%\bin\dot.exe.

Verify the installation by opening a command prompt and running dot -version; a version output confirms success.

Configuring Graphviz in IntelliJ IDEA

Navigate to File → Settings → Other Settings → PlantUML and ensure the Graphviz dot executable is detected.

Drawing a Flowchart with PlantUML

Create a new .uml file in IDEA and paste the following PlantUML code:

@startuml
Alice -> Bob: Authentication Request
Bob --> Alice: Authentication Response

Alice -> Bob: Another authentication Request
Alice <-- Bob: another authentication Response
@enduml

The right-hand preview pane renders the sequence diagram in real time.

Generating UML Class Diagrams

PlantUML can also produce class diagrams from existing code. The article references a previous guide on using IDEA's built-in feature to generate UML class diagrams from project code with one click.

Alternative: Browser-Based PlantUML Viewer

If you prefer not to install Graphviz, you can use the Chrome extension PlantUML Viewer . After installation, edit PlantUML text directly in the browser and see the diagram rendered instantly.