Class diagram maker

Map complex processes using our UML class diagram creator. Build professional, data-backed diagrams in minutes with Lucidchart.

By registering, you agree to our Terms of Service and you acknowledge that you have read and understand our Privacy Policy.

Get started with our AI diagram generator

Illustration AI powered text-to-diagram feature, link to generate diagram with AI-powered text-to-diagram feature

Professional, polished UML class diagram maker

Leverage dynamic UML class diagramming capabilities designed to streamline your processes and boost productivity.

Align your team on technical logic

Eliminate ambiguity in your workflows. Map complex systems with a UML class diagram to visualize logic before committing to code and ensure your team stays aligned on every detail.

Leverage UML shape libraries and symbols

Use specialized shape libraries and industry-standard symbols to build clear, technically sound UML class diagrams.

Leverage Lucid AI

Use Lucid AI to create UML diagrams faster than ever. Simply enter text prompts to generate professional visuals and then iterate until you have the exact documentation you need.

Collaborate in real time

Invite people to view, edit, or give real-time feedback on your UML diagram using comments and @mentions. Review individual contributions by enabling collaborator colors, and use revision history to see changes or revert to a previous version.

Boost productivity with 100+ integrations

Connect Lucidchart to apps from leading providers like Google, Microsoft, and Slack. Explore the Lucid integrations marketplace for apps to streamline communication, strategic planning, task management, and more.

Lucidchart feature highlights

Real-time collaboration

Streamline work by enabling multiple collaborators to create and edit the same diagram at once.

Data linking

Create accurate diagrams faster by linking shapes to data from Google Sheets, Excel, or CSV files.

Conditional formatting

Transform data by visually highlighting patterns and insights for quick comprehension at a glance.

Layers

Add layers to visualizations for multiple levels, distinct visibility controls, and streamlined editing.

Revision history

Collaborate confidently—view changes, revert to prior versions, and ensure diagrams are up to date.

Shape libraries

Use existing shape libraries for Salesforce, enterprise architecture, and more—or customize your own.

AI prompt flow

Build and experiment with LLMs on the Lucid canvas. Test prompts and inputs to see what works best.

Lucidchart feature highlights

Streamline work by enabling multiple collaborators to create and edit the same diagram at once.

UML class diagram templates and examples

Choose a customizable template to create a UML class diagram online.

Activity diagram with swimlanes

Go to Activity diagram with swimlanes template

UML class diagram

Go to UML class diagram template

Web sequence diagram

Go to Web sequence diagram template

Getting started in Lucidchart

Getting Started in Lucidchart

Follow along with this video tutorial and learn how to make any type of diagram in Lucidchart.

Make a diagram

Why teams choose Lucidchart

As an intelligent diagramming application, Lucidchart provides simple yet powerful capabilities for visualizing information.

Collaboration. Bring teams together side by side on a shared canvas from anywhere in the world.

Alignment. Build transparency and shared understanding of how a team or company works.

Large-scale change. Increase visibility, standardization, and knowledge sharing across your entire org.

End-to-end workflows. Upgrade to the Lucid Suite for a complete, connected visual collaboration solution.

What is a UML class diagram?

A UML (Unified Modeling Language) class diagram is essentially the blueprint of a software system. It’s a static structure diagram that describes a system's structure by showing its classes, their attributes, operations (or methods), and the relationships among objects. Think of it as a blueprint of your code before you actually write it.

Steps to drawing a UML class diagram

Identify the primary objects (classes)

Start by looking at your problem statement or requirements. High-value "nouns" are usually your classes. If you are building an e-commerce app, your initial classes are likely Customer, Order, Product, and ShoppingCart.

Define attributes (data)

Determine what data each class needs to store. For a Customer class, this might be name, email, and phoneNumber. Don't forget to include the visibility.

Determine operations (methods)

What can these objects do? A ShoppingCart might need addItem( ), removeItem( ), and calculateTotal( ). List these in the bottom third of your class box with their return types.

Establish relationships

This is where the map comes together. Determine how the classes interact:

Inheritance: Is one class a specific version of another? (e.g., CreditCard and PayPal both inherit from PaymentMethod).
Association: Does one class just use another? (e.g., a Customer places an Order).
Multiplicity: How many of "A" belong to "B"? (e.g., 1 Order can have 1 to many Products).

Define composition vs. aggregation

Refine your associations by looking at the life cycle of the objects:

Composition (filled diamond): If the parent is deleted, the child is destroyed too (e.g., House and Room).
Aggregation (hollow diamond): The child can exist independently (e.g., Department and Professor).

Publish and share

Share your UML diagram with other teams or stakeholders. Embed your diagram in a wiki, send it in an email, or share it with integrations like Jira, Confluence, and Slack.

Additional Lucidchart resources

Lucid Training Labs

Learn visual collaboration skills in free, self-serve courses and live training workshops.

Explore courses

Lucid Community

Connect with other users to share tips and insights. Provide feedback to Lucid’s product team.

Join now

Help center

Find detailed articles with step-by-step instructions for using specific Lucid features.

Search resources

Lucidchart tutorials

Go to the Lucidchart tutorials playlist on YouTube for video training on various topics.

Explore playlist

Collaborate with AI

Get an overview of Lucid’s AI functionality and find additional resources.

See what’s possible

Lucid blog

Explore tips for optimizing collaboration, aligning teams, and driving initiatives in Lucidspark.

Read now

Lucidchart pricing

Create a free account and compare options for paid Individual, Team, or Enterprise plans.

Compare plans

Frequently asked questions about UML diagrams

Can I build a UML diagram using markup?

Yes. First, you will need to enable the UML sequence diagram shape library. Then, Lucidchart provides a UML sequence markup feature that auto-generates a sequence diagram based on the text you provide.

How can I change the formatting of a UML diagram?

You can add styling and formatting to your UML diagram using the Properties bar at the top of the Lucidchart editor.

Can I show the difference between current and future states within the UML diagram?

Yes, use the layers feature to visualize current, ideal, or future states of any process or system side by side. Start with your current system and then create a layer depicting future states. Use hotspots to toggle between layers.

Learn more

What are the options for sharing my UML diagram in Lucidchart?

Publish and share diagrams with Lucidchart users and non-users via email, shared link, PDF, or image file. You can also share your diagram on social media or embed it onto any webpage.

Everything you need to make a diagram

In addition to our online UML class diagram tool, Lucidchart offers support and training resources to help you branch out to any type of diagram.

Lucid Training