UMLet

Name: UMLet
Author: UMLet

Free plan ExtensionLinuxMacWebWindows

What UMLet is

UMLet is a free, open-source tool for quickly sketching UML diagrams. It supports class, use case, sequence, state, deployment, and activity diagrams. To edit a diagram element, users change its text in UMLet’s small markup dialect rather than configuring it through pop-up dialogs. The tool is available as a stand-alone desktop app, an Eclipse plugin, the browser-based UMLetino, and a Visual Studio Code extension.

The stand-alone app exports diagrams to BMP, EPS, GIF, JPG, PDF, PNG, and SVG, and can copy them to the clipboard. It also supports command-line batch conversion of UXF files to formats such as PDF. UMLetino runs in a browser without installation, stores diagrams in browser storage, and exports PNG. Users can make custom UML elements by writing Java code that UMLet compiles on the fly, but this capability is limited to the stand-alone app. The desktop app runs on Java platforms such as Windows, Linux, and macOS, and requires Java to be installed. UMLet identifies its license as GNU GPL 3.0. It does not generate code from models or reverse-generate models from code, and its FAQ says round-trip engineering is not planned. The project accepts bug reports and feedback by email or GitHub ticket.

Who it suits

UMLet suits people who want a free tool for sketching UML diagrams and prefer editing diagram elements as text. It can also suit users who need desktop exports, batch conversion, or custom elements written in Java.

What it does well

Free and open source under GNU GPL 3.0.
Supports six UML diagram types.
Desktop exports include PDF, PNG, and SVG.
Browser version runs without installation and exports PNG.
Desktop app supports command-line batch conversion of UXF files.

What to know first

Desktop use requires Java to be installed.
Custom Java elements are available only in the stand-alone app.
It does not generate code from diagrams or reverse-generate models.

Plans

Plan	Billed and limits	Price
UMLet	Free, open-source UML tool · stand-alone app for Windows, macOS, and Linux; Eclipse plugin · web app and VS Code extension	Free
UMLetino	Free online UML tool · runs in browser · saves diagrams in browser storage · PNG export	Free

As umlet.com lists them, read 7 Oct 2026. The maker's own page has the final word.

Getting started

Visit https://www.umlet.com/.
Choose the stand-alone app, Eclipse plugin, UMLetino browser app, or Visual Studio Code extension.
For the stand-alone app, install Java on Windows, Linux, or macOS.
Create diagrams by editing UML element text in UMLet’s markup dialect.
Use the stand-alone app for desktop exports or batch conversion; use UMLetino for PNG export.

Verdict

Choose UMLet for free UML sketching across desktop, browser, Eclipse, or Visual Studio Code. Its text-based editing and broad desktop export formats suit quick diagram work. Look elsewhere if you need code generation or round-trip engineering.

Questions

Does UMLet cost anything?

No. UMLet and UMLetino are listed as free.

Is UMLet open source?

Yes. UMLet identifies its license as GNU GPL 3.0.

Which diagram types does it support?

It supports class, use case, sequence, state, deployment, and activity diagrams.

Which platforms or versions are available?

UMLet offers a stand-alone app for Windows, macOS, and Linux, an Eclipse plugin, a browser app called UMLetino, and a Visual Studio Code extension. The stand-alone app requires Java.

Which export formats are available?

The stand-alone app exports BMP, EPS, GIF, JPG, PDF, PNG, and SVG, and copies diagrams to the clipboard. UMLetino exports PNG.

Can UMLet generate code from diagrams?

No. It does not generate code from models or reverse-generate models from code, and its FAQ says round-trip engineering is not planned.

Facts from UMLet's own pages

Batch conversion: The stand-alone application supports command-line batch conversion of UXF files to formats such as PDF. · umlet.com, 7 Oct 2026
Browser storage: UMLetino runs in a browser without installation and saves diagrams in browser storage. · umletino.com, 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, 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, 7 Oct 2026
Desktop apps: Yes · umlet.com, 20 Sept 2026
Diagram types: UMLet supports class, use case, sequence, state, deployment, and activity diagrams. · umlet.com, 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, 7 Oct 2026
Founded: 2001 · umlet.com, 28 Sept 2026
Free plan: Yes · umlet.com, 20 Sept 2026
Import/export formats: UXF; BMP,EPS,GIF,JPG,PDF,PNG,SVG · umlet.com, 20 Sept 2026
Integrations: UMLet is available as a stand-alone app, Eclipse plugin, browser app called UMLetino, and Visual Studio Code extension. · umlet.com, 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, 7 Oct 2026
License: The UMLet site identifies the software as open source under GNU GPL 3.0. · umlet.com, 7 Oct 2026
Purpose: UMLet is a free, open-source UML tool aimed at creating UML sketches quickly. · umlet.com, 7 Oct 2026
Security update: The change history lists an XML security fix in UMLet 14.3. · umlet.com, 7 Oct 2026
Support: The project asks users to email [email protected] or create a GitHub ticket for bugs and feedback. · umlet.com, 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, 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, 7 Oct 2026