How to Generate UML Class Diagrams from Your Codebase

UML class diagrams show the structure of your code: classes, their attributes and methods, and the relationships between them. They're invaluable for documentation, code reviews, and onboarding — but keeping them in sync with code is a constant battle. Here's how to generate them automatically.

What a Class Diagram Shows

• Classes with their attributes (fields/properties) and methods.
• Visibility modifiers: public (+), private (-), protected (#).
• Relationships: inheritance, composition, aggregation, association.
• Interfaces and abstract classes.
• Cardinality of relationships (1..*, 0..1, etc.).

The Problem with Manual Class Diagrams

Manual UML class diagrams go stale the moment code changes. A renamed field, a new method, or a refactored inheritance hierarchy makes the diagram inaccurate. Developers stop trusting stale diagrams, so they stop looking at them. The solution is automated generation.

Generate from Code with ArchitectAI

Paste your class definitions or module structure into ArchitectAI and describe what you want: "Generate a UML class diagram showing the relationships between User, Order, Product, and Payment classes." The AI analyzes the code structure and produces a clean class diagram with proper UML notation.

class User:
    id: int
    email: str
    orders: List[Order]

class Order:
    id: int
    user_id: int
    items: List[OrderItem]
    total: Decimal

class OrderItem:
    product: Product
    quantity: int
    price: Decimal

Feed this to ArchitectAI and it generates a UML class diagram showing User has a one-to-many relationship with Order, Order has a one-to-many with OrderItem, and OrderItem has an association with Product — all with proper UML notation.

Best Practices

• Focus on the domain model: Don't include utility classes or framework internals.
• Show relationships, not just classes: The value is in how things connect.
• Keep it high-level: For large codebases, create multiple diagrams for different modules.
• Regenerate regularly: Treat diagrams as generated artifacts, not hand-maintained documents.