Free Class Diagram Generator

Create UML class diagrams instantly with our free AI generator. Design class diagrams for Java, Python, and any OOP project. No design skills needed.

Class diagram of a library management system

Class diagram of an e-commerce platform

Class diagram of a student management system

Class diagram of a banking application

Class diagram of a hotel reservation system

What is a Class Diagram?

A class diagram is a UML (Unified Modeling Language) diagram that shows the structure of a software system. It visualizes classes, their attributes (properties), methods (functions), and the relationships between them.

Class diagrams are essential for object-oriented design (plan your classes before coding), documentation (communicate system architecture to your team), and code generation (some tools generate code from class diagrams).

Whether you're designing a Java application, Python project, or any OOP system, a class diagram helps you think through your design before writing code.

What Can You Create?

Software Architecture

Design the class structure for applications, APIs, and microservices. Visualize how components interact before implementation.

Java & OOP Projects

Model Java classes with inheritance, interfaces, and associations. Perfect for students learning object-oriented programming.

Domain Modeling

Create domain model class diagrams that map business concepts to software objects. Essential for DDD (Domain-Driven Design) projects.

Technical Documentation

Generate clear diagrams for project documentation, code reviews, and onboarding new team members.

UML Class Diagram Basics

Class diagrams use standard UML notation:

Classes

Rectangles divided into three sections: Top (Class name), Middle (Attributes like - name: String), Bottom (Methods like + getName(): String)

Relationships

Association — Basic connection between classes
Inheritance — Arrow pointing to parent class
Composition — Filled diamond (strong ownership)
Aggregation — Empty diamond (weak ownership)

Visibility markers

+ Public
- Private
# Protected

Our AI generator handles the notation automatically—just describe your classes and relationships in plain English.

Create Class Diagrams with AI

Skip the manual drawing. Describe your system and let AI generate a properly formatted UML class diagram.

How it works:

Describe your classes: "User class with name and email, Order class with items and total, User has many Orders"
AI generates the diagram with correct UML notation
Download in high resolution (2K/4K)

Works for any language—Java, Python, C#, TypeScript, or language-agnostic design.

Create Class Diagram with AI →

Frequently Asked Questions

Related Diagram Tools

Explore other diagram types for software design:

ER Diagrams — Database structure design

UML Diagrams — Comprehensive software modeling

Sequence Diagrams — Interaction flows

One Diagram. Different Styles.

Don't settle for generic visuals. Match your diagram's aesthetic to your brand identity with our Style Picker.

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Free Class Diagram Generator

What is a Class Diagram?