Class Diagram Template

What this template is for

A UML class diagram template gives you a ready-made structure for designing and documenting object-oriented systems. This template shows classes with attributes and methods, inheritance hierarchies, associations, and dependency relationships — the core building blocks you need before writing a single line of code. Use it in backend design sessions, code reviews, or when onboarding new engineers to an unfamiliar codebase.

When to use this template

• Design a new domain model before starting a sprint so engineers share a common understanding of the data structure.
• Document an existing codebase for a new team member who needs to understand the architecture quickly.
• Review a proposed design change in a code review by visualizing what changes before approving a PR.
• Communicate a database schema design to non-technical stakeholders using a class diagram instead of raw SQL.
• Detect coupling and circular dependencies visually before they become production problems.

How to use it

1. 1Identify the main entities in your domain — each becomes a class box with a name, attribute list, and method list.
2. 2Add attributes with their types and visibility modifiers: + (public), - (private), # (protected).
3. 3List the key methods with their signatures and return types.
4. 4Draw inheritance arrows (solid line with hollow arrowhead) from child classes to parent classes.
5. 5Add association lines between classes that reference each other, with multiplicity labels (1, 0..*, 1..*).
6. 6Use dependency arrows (dashed lines) for weaker, usage-based relationships.

Quick example

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