How to Get Started with UMLet

Updated

Download UMLet 15.1 as a stand-alone app for Windows, macOS, or Linux, or use it as an Eclipse plugin, a Visual Studio Code extension, or the web app UMLetino — then draw your first diagram by double-clicking to add elements and editing them in the lower-right text panel. This quickstart suits anyone who wants fast UML sketches without pop-up dialogs; the trade-off is that element editing happens through text and a small markdown dialect rather than a graphical property editor. UMLet is described as a free, open-source UML tool.

Choose how you want to run UMLet

Option Best for Notes from the site
Stand-alone app Windows, macOS, Linux desktop use Full-featured version
Eclipse plugin Existing Eclipse users Listed as an integration option
VS Code extension VS Code users Available on the VS Code Marketplace
UMLetino (web app) Quick browser-based sketching Web version of UMLet

The site also links to the GitHub repository (github.com/umlet) and lists contact addresses ([email protected]) and a Twitter handle (@twumlet). If you want to support the project, the site mentions sponsoring via GitHub, Patreon, or PayPal.

Draw your first diagram

  1. Add an element — double-click to add elements to a UML diagram.
  2. Edit the element — use the lower-right text panel. Elements are modified through text input and a small markdown dialect instead of pop-up dialogs.
  3. Get help while typing — press Ctrl+Space for context-sensitive help.
  4. Select multiple elements — use Ctrl or a lasso selection.
  5. Copy the diagram — press 'C' to copy it to the system clipboard.
  6. Zoom — use +/- or Ctrl+mousewheel.
  7. Avoid sticking relations — press Shift.

The expected result after these steps is a diagram you can keep editing in text form and export when ready.

Export and share

UMLet exports to eps, pdf, jpg, svg, and the clipboard. Version 15.0 added hi-res export, so if you need a sharper image, that capability is available in current releases.

Reuse and customize elements

  • Elements can be modified inside their palettes and immediately used as new templates, so you can tailor UMLet to your modeling needs.
  • You can create your own custom UML elements. An element's look can be modified at run-time by changing a few lines of Java code, and UMLet compiles the new element's code on the fly — without leaving UMLet.
  • Learning about element features is supported by prototypically using them from sample palettes.

Supported diagram types

UMLet supports class diagrams, use case diagrams, sequence diagrams, state diagrams, deployment diagrams, and activity diagrams. The site points to sample diagrams and examples for each.

What changed recently

  • 15.1 — relation bug fix, log lib update, dark mode cleanup.
  • 15.0 — web zoom, lasso, export, dark mode; hi-res export; startup improvements.
  • 14.3 — improved OS and Eclipse integration; XML security fix.

Common sticking points

  • Editing feels unusual at first — this is by design: UMLet uses text input and a small markdown dialect rather than dialogs. Use Ctrl+Space when unsure.
  • Relations stick when you don't want them to — hold Shift.
  • You need a different runtime — if the stand-alone app doesn't fit your workflow, the Eclipse plugin, VS Code extension, or UMLetino web app are alternatives listed on the site.

For bugs or requests, the site suggests creating a code ticket or emailing [email protected].