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JetUML
What it is
JetUML is a free desktop UML editor for quickly sketching software design ideas on Windows, macOS, and Linux. It focuses on a minimalist set of core diagramming features and supports class, sequence, state, object, and use case diagrams. Association edges receive automatic layouts, with paths changing when nodes move. The editor checks diagram validity and reports problems through temporary notifications. Diagrams can be exported as SVG, PNG, or JPEG images, or copied to the system clipboard for use elsewhere. JetUML stores diagrams as JSON in a documented open format, with a schema for each diagram type. The application is distributed as Java archives, including an operating-system-independent archive that requires Java and JavaFX; a community Nix package is available for macOS and Linux. JetUML is released under the GNU General Public License version 3 or later. The project states that it collects no information and accesses the network only to open web pages through Help menu commands. Larger diagrams can reduce application performance.
For and against
For
- Free and open-source under GPLv3 or later
- Supports five UML diagram types
- Automatically lays out association edges
- Exports SVG, PNG, and JPEG
- Stores diagrams in documented JSON
Against
- Larger diagrams can reduce performance
- Some archives require Java and JavaFX
- Desktop application rather than mobile
The verdict
JetUML keeps UML sketching focused on core diagram types, automatic edge layout, validation, and straightforward export. Its open format and cross-platform desktop distribution suit lightweight design work, while larger diagrams may affect performance.
Who it suits
JetUML suits developers, students, and designers who want a focused desktop tool for sketching core UML diagrams. It is available across Windows, macOS, and Linux.
Plans and prices
JetUML
Free and open-source UML editor · GNU General Public License v3
Read 7 Oct 2026 · jetuml.org
On the record
- Automatic layout
- JetUML automatically lays out association edges, and moving nodes changes their paths.jetuml.org · read 7 Oct 2026
- Diagram types
- It supports class, sequence, state, object, and use case diagrams.jetuml.org · read 7 Oct 2026
- Export and clipboard
- Diagrams can be exported as images, including SVG, PNG, and JPEG, or copied to the system clipboard for use in other applications.jetuml.org · read 7 Oct 2026
- File format
- JetUML stores diagrams as JSON using a documented open format, with a schema for each diagram type.jetuml.org · read 7 Oct 2026
- Intended use
- The project describes its focus as a minimalist set of core UML diagramming features for fast sketching.jetuml.org · read 7 Oct 2026
- License
- The application is distributed under the GNU General Public License version 3 or later.jetuml.org · read 7 Oct 2026
- Notable limitation
- The user guide says larger diagrams decrease application performance.jetuml.org · read 7 Oct 2026
- Platforms and installation
- The application is distributed as Java archives, including an OS-independent archive requiring Java and JavaFX; a community Nix package is available for macOS and Linux.jetuml.org · read 7 Oct 2026
- Privacy
- JetUML states that it collects no information and accesses the network only to open web pages through Help menu commands.jetuml.org · read 7 Oct 2026
- Purpose
- JetUML is a desktop UML editor for quickly sketching software design ideas.jetuml.org · read 7 Oct 2026
- Support
- The project invites users to send endorsements to [email protected] and to support it by starring its GitHub repository.jetuml.org · read 7 Oct 2026
- Validation
- It checks diagram validity and reports problems with temporary notifications.jetuml.org · read 7 Oct 2026
