UMLet
UMLet · founded 2001
What it is
UMLet is a free, open-source tool for quickly sketching UML and other diagrams. It supports class, use case, sequence, state, deployment, and activity diagrams. Instead of configuring elements through pop-up dialogs, users edit text in a small markup dialect. UMLet is available as a stand-alone desktop app, an Eclipse plugin, the UMLetino browser app, and a Visual Studio Code extension. The desktop application can export diagrams to BMP, EPS, GIF, JPG, PDF, PNG, and SVG, copy them to the clipboard, and batch-convert UXF files through the command line. UMLetino runs without installation, saves diagrams in browser storage, and offers PNG export. Users can create custom UML elements with Java code, but that capability is limited to the stand-alone version. The desktop app requires Java on Windows, Linux, or macOS. UMLet is licensed under GNU GPL 3.0 and does not provide code generation from models or reverse generation from code.
For and against
For
- Free and open source under GNU GPL 3.0.
- Supports six listed UML diagram types.
- Desktop app exports to seven image and document formats.
- Browser app runs without installation.
- Supports command-line batch conversion of UXF files.
Against
- Desktop application requires Java.
- Custom elements are limited to the stand-alone version.
- No code generation or reverse generation.
- UMLetino saves diagrams in browser storage.
The verdict
UMLet focuses on fast diagram sketching, with several ways to access it and broad desktop export options. Its lack of code generation and the desktop Java requirement are important limits to consider.
Who it suits
UMLet suits people who want a free tool for sketching UML diagrams through text-based element editing. It may work for users who need desktop, browser, Eclipse, or VS Code access, but not code generation or round-trip engineering.
Plans and prices
UMLet
Free, open-source UML tool · stand-alone app for Windows, macOS, and Linux; Eclipse plugin · web app and VS Code extension
Read 7 Oct 2026 · umlet.com
UMLetino
Free online UML tool · runs in browser · saves diagrams in browser storage · PNG export
Read 7 Oct 2026 · umletino.com
On the record
- Batch conversion
- The stand-alone application supports command-line batch conversion of UXF files to formats such as PDF.umlet.com · read 7 Oct 2026
- Browser storage
- UMLetino runs in a browser without installation and saves diagrams in browser storage.umletino.com · read 7 Oct 2026
- Code generation limit
- UMLet does not provide code generation from models or reverse generation from code, and its FAQ says round-trip engineering is not planned.umlet.com · read 7 Oct 2026
- Custom elements
- Users can create custom UML elements by writing Java code that UMLet compiles on the fly; the marketplace says this is available in the stand-alone version only.marketplace.visualstudio.com · read 7 Oct 2026
- Desktop apps
- Yesumlet.com · read 20 Sep 2026
- Diagram types
- UMLet supports class, use case, sequence, state, deployment, and activity diagrams.umlet.com · read 7 Oct 2026
- Exports
- The stand-alone application can export diagrams to BMP, EPS, GIF, JPG, PDF, PNG, and SVG, and copy diagrams to the clipboard.umlet.com · read 7 Oct 2026
- Import/export formats
- UXF; BMP,EPS,GIF,JPG,PDF,PNG,SVGumlet.com · read 20 Sep 2026
- Integrations
- UMLet is available as a stand-alone app, Eclipse plugin, browser app called UMLetino, and Visual Studio Code extension.umlet.com · read 7 Oct 2026
- Intended use
- The marketplace describes UMLet's main goal as allowing users to sketch UML and other diagrams quickly.marketplace.visualstudio.com · read 7 Oct 2026
- License
- The UMLet site identifies the software as open source under GNU GPL 3.0.umlet.com · read 7 Oct 2026
- Purpose
- UMLet is a free, open-source UML tool aimed at creating UML sketches quickly.umlet.com · read 7 Oct 2026
- Security update
- The change history lists an XML security fix in UMLet 14.3.umlet.com · read 7 Oct 2026
- Support
- The project asks users to email [email protected] or create a GitHub ticket for bugs and feedback.umlet.com · read 7 Oct 2026
- System requirements
- The FAQ says the stand-alone application runs on Java platforms such as Windows, Linux, and macOS, and requires Java to be installed.umlet.com · read 7 Oct 2026
- Text-based editing
- Users modify UML elements by editing text in a small markup dialect instead of using pop-up dialogs.umlet.com · read 7 Oct 2026
