UMLet – Free UML Tools for fast UML diagrams

UMLet is a UML tool aimed at providing a fast way of creating UML sketches. UML elements are modified using text input and a small markdown dialect instead of pop-up dialogs. This core idea is described in a paper.

Learning about the various element features is supported by prototypically using them from sample palettes. Elements can also be modified inside their palettes and immediately used as new templates; this way, users can easily tailor UMLet to their modeling needs.

UMLet also allows users to create their own custom UML elements. An element’s look can be modified at run-time by changing a few lines of Java code; UMLet then compiles the new element’s code on the fly. Without leaving UMLet, users can thus create and add new element types to their diagrams. These custom elements are outlined here or in this paper.

UMLet supports a variety of UML diagram types: class diagrams, use case diagrams, sequence diagrams, state diagrams, deployment diagrams, activity diagrams — see some examples.

Finally, porting UMLet to a JavaScript web app, and later to a VS Code extension, is described

Finally, porting UMLet to a JavaScript web app, and later to a VS Code extension, is described here . And a brief history in tweets reminisces about the days of old.