UML Diagram or Unified Modeling Language Diagram is a collection of diagrams to help you visualize a software program. Thus, these diagrams are a combination of activities and action sequences that focus on time period specific processes. We suggest these great free UML diagram tools to help you make use of UML diagrams for your convenience.

Best Free Online UML diagram tools

GitMind

UML tools are software applications which support some functions of the Unified Modeling Language. UML diagram tool Lucidchart is a visual workspace that combines diagramming, data visualization, and collaboration to accelerate understanding and drive innovation.

Score: 4.8 / 5

• Online & Free UML diagram tool. Create professional visualizations of your business processes with our free UML tool. 100+ diagramming templates. Complete UML stencils set. Real-time collaboration. Used by 2,000,000 people worldwide. Create my UML diagram now No credit card required.
• Finding a Free UML Tool? Visual Paradigm Online (VP Online) Free Edition is a free online drawing tool that supports UML, ERD, Organization Chart, etc. It features a simple, intuitive yet powerful UML editor, which allows you to create professional UML diagrams smoothly and quickly.The free UML tool comes with no ad, no limited period of access and no limitations such as, number of diagrams.
• Easily create beautiful UML Diagrams from simple textual description. There are also numerous kind of available diagrams. It's also possible to export images in PNG, LaTeX, EPS, SVG.

Pricing: Free

Transform simple ideas into comprehensive and interactive content. GitMind is an excellent online platform where you can create different diagrams including UML for free. Using this as your daily UML diagram creator gives you access to customizable templates that are also available to help you make UML diagrams quickly and simply. Moreover, it has a friendly user interface that displays editing features for a hassle-free editing experience.

Visual Paradigm

Score: 4.1 / 5

Pricing: Free; $4 for a starter plan; $9 for advanced

Another intuitive and powerful UML diagram software is Visual Paradigm. You can save time and effort by choosing from one of its built-in temples to get started. Another interesting feature is that it shows you the editing components whenever you hover over the interface.

Violet UML editor

Score: 4.2 / 5

Pricing: Free

Violet UML Editor is another UML diagram tool that is very easy to learn and to use. It is a cross-platform tool intended for students, developers, and authors who need to make UML diagrams quickly. The good thing about this tool is that it is a portable program that you can copy to your flash drive or any device, so you may take it with you whenever you need to create diagrams without any complicated installation process.

Software Ideas Modeler

Score: 4 / 5

Pricing: Free; starts at $68

The next UML diagram software worth using is Software Ideas Modeler. This features quick and easy drawing tools to help create documents such as PDF and RTF, designing and styling options, Source Code Generation like C++, Java, and more. Moreover, depending on the template you’ve selected, you can insert images and any other objects to your diagram. Just simple drag and drop them in the editing area.

UMLet 14.3

Score: 3.8 / 5

Pricing: Free

The list of UML diagram tools is not complete without UMLet 14.3. This is an open-source built-in application for Windows that will help you make UML Diagrams for free. Its main features include built-in temples, and it allows you to build a sequence and a diagram of your activities from plain text. Meanwhile, it supports exporting different file types like eps, pdf, jpg, SVG, and clipboard.

Uml Diagram Tool Visio

ConceptDraw Diagram

Score: 4.6 / 5

Pricing: Free

ConceptDraw Diagram is an impressive UML diagram creator accessible on both Windows and Mac. This awesome tool is well suited for UML diagrams as it offers a number of solutions with vector stencils and templates for any project you need. Another good thing about this tool is that you can use GIF images to have an animated slide on your drawing for technical purposes.

Visio

Score: 4.8 / 5

Pricing: Free; $13/ month, $299 for standard, and $589.99 for Professional

Visio is a professional UML diagram software you may use in creating UML diagrams. It offers templates and modern UI. Thus, this feature can bring your diagrams to life with data icons, overlays, graphics, and colors for better visualizations.

Umbrello

Score: 43.7 / 5

Pricing: Free

Umbrello allows you to create diagrams in a standard composition to document or design format. Similar to other UML diagram tools, it supports sequence diagrams to help you show the order of the interaction and how the operations are carried out. Moreover, it also supports a number of code generators such as ActionScript, Java, Javascript, Pascal, etc.

Conclusion

These are the best free online UML diagram tools available. Each tool offers its own unique features for you to choose from. Meanwhile, if you are looking for the easiest and a totally free tool, GitMind is the best for you.

umlet.com -- info@umlet.com -- patreon.com/umlet

>> For a new diagram, create an empty text file with a '.uxf'-extension! <<

Then you can

• double click on a UML element in the palette;
• edit it in the lower-right markdown panel; or
• drag the background to move the whole diagram.

You're ready to go -- enjoy!

UMLet is a free, open-source UML tool with a simple user interface: draw UML diagrams fast, build sequence and activity diagrams from plain text, export diagrams to eps, pdf, jpg, svg, and clipboard, and create new custom UML elements.

It runs

• as stand-alone UMLet on Windows, macOS, and Linux;
• as Eclipse plug-in;
• as Web-based app UMLetino; and
• as VS Code extension.

The stand-alone version has the most extensive feature set; here is a brief tutorial video.

Early UML tools were often a bit cumbersome -- they relied on pop-up windows to set attributes, and aimed at model consistency up to an ever-allusive round-trip engineering.

UMLet main goal is to allow users to sketch UML (and other) diagrams fast.

• It uses a pop-up-free, markdown-based way of quickly editing elements. Even the direction or type of a relation is changed with just a few keystrokes.

• It lets users learn about UML elements of various complexity by providing palettes of many element variants as templates or prototypes. Just double-click on any element and tweak the clone. You can even modify the palettes as if you'd edit a normal diagram -- no more icon guessing.

• It supports more complex element types like activity or sequence diagrams, with their own tailored markdown dialect. With more generic, non-UML elements, you can even draw any kind of 'boxy' diagram usually done in Word or PowerPoint.

• It allows users to create their own custom 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 and displays it. Without leaving UMLet, users can thus create and add new graphical element types. (Stand-alone only, for now.)

• It provides simple batch processing on the command line. You can thus convert the uxf-format (an XML dialect) to various file formats, e.g., for you LaTeX workflow.

• Play with our codebase, or create tickets on Github.

• Find more examples in our screenshots and sample diagrams.

• Read about UMLet's underlying ideas in our papers.

Uml Diagram Tool Online

One technical issue still niggles us: handling copy/paste commands if triggerend via the menu on Windows, as there the focus is lost. We also use a 'custom visual editor' -- those are just a bit problematic as activeTextEditor becomes null if another custom editor gets activated.. If you have any idea to better our current heuristic, let us know (and claim our bottle of Italian red)!

We highly appreciate your support!

Astah

• Please send feedback and bug reports to info@umlet.com, or create a ticket on Github. Especially if you teach UML, let us know which element types you're still missing.

• Follow @twumlet on Twitter, or visit us on Facebook.

• If you like UMLet, please find the time to rate it -- we'd really enjoy that!

• (Finally, *cough*, we're also on PayPal and Patreon.)

Uml Diagram Tool Free

To our past contributors (chronologically) Thomas Tschurtschenthaler, Ludwig Meyer, Johannes Pölz, Elisabeth Blümelhuber, Julian Thöndel, and Thomas Bretterbauer: thanks! The UMLet Team -- Martin Auer, Andreas Fürnweger

Uml Diagram Tool Online

umlet.com -- info@umlet.com -- patreon.com/umlet