8 Best FREE UML Diagram Tools & Software (2025)
Amelia Parker
UML diagram tools are essential in visualizing software architecture through structured, object-oriented models that enhance clarity and development precision. Choosing the best free UML diagram tools enables professionals to design systems effectively without financial constraints. These tools translate complex processes into comprehensible formats, supporting agile workflows and technical communication. I trust high-quality free UML diagram software tools to streamline system planning.
After investing over 140 hours reviewing more than 30 UML diagram software tools, I created this exclusive, insightful overview of the best free UML diagram tools. It includes a transparent breakdown of features, pros and cons, and pricing. I once used a promising free UML diagram tool that lacked version control. That experience shaped this carefully handpicked list—a go-to source for safe, credible, and professional software choices. Read more…
Miro is a best UML diagram software tools that offers an engaging and visual environment that helps you easily bring your ideas to life. It offers a selection of pre-built UML diagram templates that help you quickly get started.
Best UML Diagram Software & Tool (Open Source & Online)
| Name | Collaboration | Customization | Free Trial | Link |
|---|---|---|---|---|
👍 Miro |
Real-time Collaboration | Moderate | Lifetime Free Basic Plan | Learn More |
 EdrawMax |
Real-time Collaboration | High | 15-Days Free Trial | Learn More |
 Adobe Express |
Yes | High | Lifetime Free Basic Plan | Learn More |
 Visme |
Comments, Content Locking | High | Lifetime Free Basic Plan | Learn More |
 Creately |
Yes | High | Lifetime Free Basic Plan | Learn More |
1) Miro
Miro is a great option, and I tested it while compiling this list of the best UML diagram software tools. It offers an engaging and visual environment that helps you easily bring your ideas to life. I particularly appreciate how it includes a comprehensive set of UML shapes and powerful file support. Miro is ideal for teams working remotely since the real-time collaboration features enhance group communication. Consider it if you want speed and flexibility without compromising quality.
It is important to note that the AI features also add extra value for faster drafting. During my review process, I tested the collaboration feature with a peer. We updated the same diagram in real time, and it felt like we were working side by side—without being in the same room.
Integration: Jira, Airtable, Coda, and etc.
Supported Diagrams: UML, Class, Sequence, Component, State Machine, etc
Multi-file Support: Yes
Free Trial: Lifetime Free Basic Plan
Features:
- Ready-made Templates: Miro offers a selection of pre-built UML diagram templates that help you quickly get started. These templates cater to different diagram types, reducing the time spent on setup and allowing you to focus on the content. Whether you’re working on class, sequence, or use case diagrams, templates ensure consistency in structure.
- Shape Library: Miro provides an extensive library of UML shapes, ensuring accuracy and standardization in your diagrams. You can easily find shapes for classes, objects, actors, and more. One thing I noticed is that using the correct shapes straight away prevents confusion during team reviews. The shape library helps maintain clarity and professionalism in your diagrams.
- Drag-and-Drop Functionality: Miro’s intuitive drag-and-drop feature makes creating UML diagrams fast and easy. Elements can be placed on the canvas by simply dragging them from the toolbar, which significantly simplifies the process. While testing this feature, I found that grouping related elements saved me time and kept the diagram organized.
- Interactive Flow Indicators: Miro provides arrows and connectors to illustrate relationships between components. These flow indicators help clarify the interaction within the diagram. There is also an option that lets you adjust the arrow styles to distinguish between different types of relationships, which enhances diagram clarity.
- Zoom and Pan: Navigating large UML diagrams becomes easier with Miro’s zoom and pan functionality. You can quickly zoom in on details or pan to view the complete diagram, which is particularly useful for complex projects. While working on detailed systems, I found that setting specific zoom levels for different diagram sections kept everything manageable.
Pros
Cons
👉 How to Get Miro for Free?
- Visit the official Miro website and sign up for free using your work email address.
- MIro will send a verification link to the provided email address. You can click on that link to access the Miro UML diagramming tool for free.
Lifetime Free Basic Plan
2) EdrawMax
EdrawMax has impressed me as a versatile diagramming platform that makes UML diagram creation simple and structured. I reviewed its features thoroughly and found it ideal for teams who want to create diagrams without dealing with clunky interfaces. It supports nearly all formats you might need, like Visio, Word, and SVG.
The free cloud storage and secure data encryption give an extra edge. This software made it easier for me to present clean visual documentation even under tight deadlines. My hands-on experience: I created a class diagram within minutes using drag-and-drop templates. It felt effortless and saved me a lot of time.
Integration: Microsoft Visio, Dropbox, and Google Drive
Supported Diagrams: Flowchart, Mind Map, Org Chart, Gantt Chart, etc.
Multi-file Support: No
Free Trial: 15 Days Free Trial
Features:
- Easy modeling: The tool provides an easy method for transitioning from UML to domain-specific modeling. It lets you constantly add new features based on user feedback. EdrawMax also allows users to reuse provided representations and work in total transparency on both DSL and UML models.
- Real-Time Collaboration: Teams can co-edit UML diagrams in real time, making remote collaboration seamless. I used this feature during a sprint planning session with my development team across three time zones. It eliminated back-and-forth messaging and improved decision-making. There is also an option that lets you add live comments to diagram elements, which helps keep discussions context-specific.
- Presentation Mode: EdrawMax lets you present diagrams directly within the platform. I’ve used this feature during live demos and found it helpful in walking clients through system workflows. The transitions are smooth, and you don’t need to juggle between apps. It keeps everyone’s focus on the architecture.
- Layered Diagramming: This feature helps manage complex diagrams by grouping elements into layers. Working on a multi-tier architecture model helped me isolate business logic from data flow. It simplifies the view and reduces visual clutter, making stakeholder reviews smoother.
- Embedded Notes & Hyperlinks: You can insert notes and hyperlinks directly into diagram elements. I often used this to link documentation or explain complex interactions. It turns static diagrams into dynamic learning tools. I suggest using hyperlinks to reference system specs or code repositories for deeper context.
Pros
Cons
👉 How to Get EdrawMax for Free?
- Visit the official EdrawMax website and click on the Free Download option.
- It will download the installation file. Once downloaded, install the file to access EdrawMax for free.
7-Days Free Trial
3) Adobe Express
When talking about the best UML diagram tools, Adobe Express deserves a solid spot on the list. Adobe Express helped me visualize my diagrams better without feeling overwhelmed by complexity. I tested its chart creation module and appreciated how it simplifies the process of structuring visual elements. It is one of the best free UML diagram tools that also supports file sharing with ease.
During my research, I noticed that its integration with Canvas LMS and 2GB cloud storage makes it a good idea to consider, especially for small teams. The collaboration features worked well in real scenarios. In fact, the tool made diagramming feel less technical and more creative. Creating a simple sequence diagram took me less than 10 minutes. I could focus more on structure and less on formatting, which truly enhanced my workflow.
Integration: Canvas LMS
Supported Diagrams: Flowchart
Multi-file Support: Yes
Free Trial: Lifetime Free Basic Plan
Features:
- Chart Variety: Adobe Express makes it easy to build pie, bar, donut, or progress charts that align well with UML workflows. You can start from a pre-made template or build from a blank canvas. The drag-and-drop tool is intuitive and flexible. I suggest mixing chart types within a single diagram to make relational data more digestible for non-technical stakeholders.
- Template Creation: You can turn any custom UML diagram into a reusable template. This saves time when working on recurring system models or collaborative projects. I used this feature during a client engagement, and it drastically reduced prep time. The tool lets you duplicate and adapt templates across workspaces so that team workflows stay consistent.
- Custom Branding: You can add logos, colors, and typography to UML diagrams to reflect your brand identity. This helps maintain visual consistency across internal and external documents. There is also an option to save branding presets, which is extremely useful for streamlining future diagrams.
- Animation Effects: Bring static UML diagrams to life with smooth transitions and subtle animations. This enhances engagement during walkthroughs or presentations. While testing this feature, I found that animating only key nodes or connectors improves focus without overwhelming the viewer.
- Design Asset Library: Adobe Express provides a diverse set of design assets that visually enhance UML diagrams. You can add UI/UX cues, structural dividers, or even mock components. I recommend integrating structural highlights from this library—they subtly reinforce diagram clarity.
Pros
Cons
👉 How to Get Adobe Express for Free?
- Visit the official Adobe Express website and click on Get Adobe Express Free.
- Adobe will ask you to login using email or Google, Facebook, etc. After login, you can select your purpose to start accessing Adobe Express design templates for free.
Lifetime Free Basic Plan
4) Visme
Visme is a flexible and visually engaging platform that makes creating UML diagrams incredibly smooth, even for beginners. It is not just about flowcharts and diagrams—it is about delivering clear, engaging visual communication through UML diagrams, infographics, graphs, and more. The interface made it possible to build free UML diagrams without any confusion. I could access multiple export formats like PDF, DOC, Excel, and more, which is quite helpful in streamlining the work process.
The tool made diagram creation smooth and productive. It is perfect for anyone seeking a simple yet powerful free UML software. The free plan’s 2GB cloud storage and robust encryption make it a top pick. I tested the interface by creating an org chart and was surprised at how effortlessly I managed layout changes and design customization without needing external help.
Integration: HubSpot, Zapier, Wistia, One Drive etc.
Supported Diagrams: ER, Class, Use Case, UML and Flowchart
Multi-file Support: Yes
Free Trial: Lifetime Free Basic Plan
Features:
- Smart Object Grouping: Automatically grouping objects and connectors brings more clarity to complex system diagrams. Visme detects logical clusters and organizes them efficiently, making it easier to present to stakeholders. While using this feature, one thing I noticed is that you can manually adjust groupings to reflect custom hierarchies, which helps during system architecture reviews.
- Advanced Customization Options: Visme offers flexible control over visual styling. You can change colors, fonts, line thickness, and more. I’ve customized diagrams to match both internal branding and client-specific styles. For consistent design across projects, I recommend creating a preset theme once and reapplying it to all future diagrams.
- Visme AI Tools: Visme’s AI-powered assistance simplifies diagram creation. It recommends structure, suggests labels, and even auto-aligns elements. I tried it on a new user flow diagram and saved a ton of time. While testing this feature, I found the AI layout suggestions surprisingly accurate, especially for sequence and activity diagrams.
- Asset Library Access: Visme’s asset library is a goldmine for diagram visuals. You get access to icons, connectors, and illustrations tailored for tech diagrams. I found it particularly helpful while designing a complex component diagram. I recommend bookmarking your most-used elements to save time on future projects.
- Content Locking: Content locking ensures critical diagram elements remain untouched. This is helpful when working with teams where accidental edits can cause errors. I’ve used this when finalizing a class diagram—it prevented key structure shifts during final reviews. You will notice that this adds an extra layer of control, especially during collaboration or training sessions.
Pros
Cons
👉 How to Get Visme for Free?
- Visit the official Visme website and click on Sign Up Free.
- After signing up, Visme will let you access the tool and it’s diagramming features for free.
Lifetime Free Basic Plan
5) Creately
Creately is a user-friendly solution that allows me to create diagrams with minimal effort and maximum impact. I would rate it among the best UML diagram software tools, which come with facilities like centralized documentation, diagram linking, and an extensive template library for software design teams. I particularly liked how quickly I could switch between diagram types without losing data.
As I evaluated its features, I found that the format export options cover every practical need. It also provides strong security coverage with AES-256 encryption, which is essential for teams dealing with proprietary models. I designed a deployment diagram using Creately’s templates and exported it as a PDF. It looked professional and needed no additional editing before sharing it with stakeholders.
Integration: Google Drive, Slack, Confluence, Zapier, OneDrive etc.
Supported Diagrams: ER, UML, Class, Sequence, Use Case and Flowchart
Multi-file Support: Yes
Free Trial: Lifetime Free Basic Plan
Features:
- Infinite Canvas: The unlimited canvas lets you map out complex systems without worrying about space. It’s beneficial for visualizing large enterprise architectures. I’ve used it to illustrate end-to-end microservices flows. I suggest zooming out periodically while diagramming to ensure logical flow and avoid cluttering specific sections.
- Data-Linked Diagrams: Creately allows linking UML elements to real-time data sources or internal documents. This gives your diagrams more context and makes them interactive. I recommend using this when modeling system behavior over time—it brings a deeper level of analysis, especially for system architects.
- Role-Based Access Control: This lets you assign viewer, editor, or commenter roles to team members. It helps manage permissions efficiently and prevents accidental edits. I recommend reviewing access levels regularly, especially when working with external collaborators or cross-functional teams.
- Embedded Diagram Sharing: Share your diagrams securely via links or embed them into wikis and web pages. It’s an efficient way to get feedback or keep stakeholders updated. I often used embedded diagrams in team Confluence pages, and they enhanced visibility significantly. To maintain information security, I suggest enabling access to expiration settings for sensitive diagrams.
- Contextual Database View: A unique feature that shows the same UML items across different views, keeping data synced in real time. It’s ideal for modeling systems from multiple perspectives. I recommend using this when documenting layered architecture—it keeps dependencies visible without duplicating components.
Pros
Cons
👉 How to Get Creately for Free?
- Visit the Creately website and click on Sign Up Free.
- After signing up, you will be redirected to the different plans page. From there, choose Continue with the Free Plan option to access Creately for free.
Lifetime Free Basic Plan
6) Lucidchart
Lucidchart is an innovative UML diagram tool that I particularly appreciate for its versatility and ease of use. It has allowed me to create complex diagrams without any steep learning curve. While conducting my evaluation, I discovered that its collaborative features are excellent for team projects, enabling everyone to contribute in real time. The ability to export in different formats ensures that sharing my work is straightforward and efficient.
For anyone seeking reliable free UML software, I highly recommend Lucidchart as one of the best options on the market. The tool not only simplifies the creation of diagrams but also enhances teamwork through its collaborative features, making it a top choice among users seeking effective solutions for their projects.
Features:
- Cloud Accessibility: Lucidchart’s UML diagram tool runs entirely in the cloud, offering seamless access from any browser or device. I’ve used it on both macOS and mobile browsers without losing functionality. This accessibility is perfect for hybrid or remote teams. There is also an option that lets you sync changes instantly, which keeps all collaborators aligned without extra effort.
- Data Linking: This feature connects diagrams to live data from spreadsheets or databases. I’ve linked class diagrams to Excel-based datasets and watched them update dynamically. It’s a powerful tool for keeping technical and business models aligned. You will notice how this helps reduce manual updates, especially in evolving system architecture models.
- Easy Sharing Options: You can share diagrams via email or public link or embed code—no account needed for viewing. I often use the direct link method for stakeholders during reviews. It simplifies feedback collection across non-technical teams. I suggest using access-expiration settings if you’re sharing confidential architecture documents.
- Embedded Comments: Collaborators can leave comments on specific shapes or sections of your diagram. I used this during code reviews to highlight system flaws visually. It leads to more targeted discussions and fewer email chains. There is also an option that lets you tag team members directly in comments, which speeds up responses.
- Role-Based Permissions: Assign viewing, commenting, or editing rights based on user roles. I once managed a cross-functional team and needed to limit editing access to developers. This feature gave me that control without restricting collaboration. While using this feature, one thing I noticed was that auditing permission logs helped prevent unauthorized changes.
Pros
Cons
👉 How to Get Lucidchart for Free?
- Visit the official Lucidchart website and click on SIgn Up Free. You can sign up using your Google, Microsoft, or Slack account.
- You will be redirected to the Lucidchart dashboard from where you can start creating UML diagrams for free.
Download link: https://www.lucidchart.com/pages/examples/uml_diagram_tool
7) StarUML
StarUML delivers a powerful diagramming experience that I found incredibly efficient. This free UML diagram toolI stores modeling data in a JSON format, making it ideal for integration with custom code generation using a Command-Line Interface (CLI). It allowed me to shift quickly between diagram types, export formats, and extensions without facing limitations. The Quick Edit feature made modeling faster than many other tools I evaluated. The extension capabilities are great for customizing according to project needs.
It is important to note how the code generation and asynchronous validation improve your productivity. In my experience, this is a top-rated choice for both individual users and teams.I could generate diagrams with minimal effort using Quick Edit. The export to PDF feature allowed me to print high-quality diagrams without formatting issues.
Features:
- Model-Driven Development: StarUML stores models in a JSON format, which makes them easily readable and integrable with external automation tools. I’ve previously connected StarUML with a CI/CD pipeline to generate documents directly from these files. There is also an option that lets you use custom scripts to transform JSON models into tailored code templates.
- Asynchronous Model Validation: Built-in model validation runs quietly in the background during file operations. This keeps your diagrams structurally correct without interrupting your workflow. While testing this feature, I appreciated how non-intrusive it felt—no annoying popups, just clean feedback. I suggest reviewing the validation log occasionally to catch subtle inconsistencies early.
- Code Generation Support: The tool supports code generation in languages like Java, C++, C#, and Python using open-source extensions. This can significantly cut down development time. I’ve used this feature to build out Java class skeletons during a sprint cycle. I recommend trying out the Java extension on GitHub for a smooth start. It’s reliable and easy to tweak.
- Command Palette Access: The Command Palette is a power feature that speeds up access to commands and extensions. It feels like using a code editor’s command bar—very efficient. I used it frequently while building a large enterprise architecture model. The tool lets you map frequent commands for even faster access, which is a productivity booster.
- Retina Display Support: StarUML supports high-resolution displays, providing sharp rendering for all elements. Diagrams look clean and professional, especially during stakeholder presentations. I’ve exported visuals for print, and the clarity remained flawless. You will notice that exports from Retina displays have more polish, especially in printed reports.
Pros
Cons
👉 How to Get StarUML for Free?
- Visit the official StarUML website from your browser.
- Click on the Download for WIndows link to start your free download. Alternatively, you can also find a Download link at the top of the home page. Clicking on that link will redirect you to a page from where you can chose different free download options (mac, WIndows, etc).
Download link: http://staruml.io/
8) Draw.IO
Draw is an excellent online tool that streamlines UML diagram creation. I have found that this platform is one of the best UML diagram tools available for free. It allows me to design diagrams with ease and flexibility. The intuitive interface makes navigating its features a breeze. I particularly liked how easily I could customize my diagrams based on my project’s needs.
In my experience with Draw, I noticed that its cloud storage feature is invaluable for collaboration. I could access my diagrams from any device, which made working on group projects much more efficient. The tool made sharing my work with teammates straightforward, enhancing our overall productivity. Overall, Draw has proven to be an impressive solution for anyone looking to create UML diagrams quickly and effectively.
Features:
- Diagram Scripting: Draw.io includes support for JavaScript-based scripting to automate diagram behaviors. This lesser-known feature is incredibly powerful. I used it to automate layout changes and add interactive elements. I suggest exploring this if you’re managing complex systems—it can save hours on repetitive edits and formatting.
- Secure Sharing Permissions: You can control who views or edits your diagrams with detailed access levels. This is especially valuable in collaborative or client-facing projects. There is also an option that lets you password-protect shared links for added security.
- Export Options: Draw.io supports formats like PNG, SVG, PDF, HTML, and XML for sharing and presentation. This ensures compatibility across documentation systems and stakeholder needs. I recommend exporting to SVG when you want scalability without quality loss, especially for presentations or publishing.
- Real-Time Collaboration: Teams can co-edit diagrams simultaneously, reducing delays and miscommunication. It supports visual cues to indicate who is editing what. I’ve led remote sprint planning sessions using this feature with impressive results. I recommend assigning diagram sections to individual team members during collaboration to prevent overlap and confusion.
- Offline Access: The downloadable desktop version ensures you can continue diagramming without an internet connection. It’s ideal for travel or secure environments where online tools are restricted. I used this feature during a client audit in a secure lab where offline capability was non-negotiable. You will notice that the desktop version performs just as efficiently as the cloud version, with no significant feature gaps.
Pros
Cons
👉 How to Get Draw for Free?
- Visit the official Draw website and select the place where you want the UML diagrams to be saved.
- After authorizing the location, Draw will let you start creating new diagrams or work on exisiting ones.
Download link: https://www.draw.io/
How did We Choose the Best Free UML Diagram Tools?
Here at Guru99, we carefully evaluate UML diagram tools to ensure they meet the diverse requirements of developers, designers, and project managers. Our selection process prioritizes functionality, ease of use, integration capabilities, and overall value for users. By focusing on tools that streamline the design and documentation process, we aim to provide recommendations that enhance productivity and collaboration across various industries.
- User-Friendly Interface: We focus on tools that offer intuitive drag-and-drop features, making it easy for both beginners and experienced users to create UML diagrams efficiently.
- Collaboration Features: Real-time collaboration capabilities are essential, allowing multiple users to work on diagrams simultaneously and enhancing teamwork.
- Integration Options: The best tools seamlessly integrate with popular platforms like Google Drive, Slack, and Jira, facilitating smoother workflows and data sharing.
- Variety of Diagram Types: We look for tools that support a wide range of UML diagrams, including class diagrams, sequence diagrams, and activity diagrams, catering to various modeling needs.
- Security Measures: Strong security protocols such as AES encryption are critical for protecting sensitive data within the UML diagrams.
- Free versions Availability: We focus on a tool’s availability of free trials or basic plans to ensure accessibility for all users.
Verdict
In this review, you got acquainted with some of the most popular UML diagram tools available at no cost. Each of these offers a unique value depending on project complexity and team collaboration. My vote for the top 3 best free UML diagram tools and software goes to the following:
- Astah: Astah delivers a reliable and customizable experience with detailed modeling options.
- Miro: Miro stands out as a user-friendly, visually engaging platform with excellent collaborative capabilities.
- Adobe Express: It helps to visualize diagrams better without feeling overwhelmed by complexity. It is one of the best free UML diagram tools that also supports file sharing with ease.
