JetUML is a free, lightweight desktop app for building and editing UML diagrams.
JetUML is built with Java which comes also in a small .jar package.
Features
It features a clean interface, a seamless responsive integration with all desktops as Linux, Windows, and macOS.

With JetUML, you can select which diagram to build:
- Class diagram
- Sequence diagram
- State diagram
- Object diagram
- Use Case diagram

JetUML allows exporting to JSON and many image file formats.
License
JetUML is released under GNU General Public License v3.