Skip to main content

What is the C4 Model?

The C4 Model is a lightweight and practical approach for visualizing the architecture of software systems. It was created by Simon Brown to provide clear and hierarchical views that help both technical and non-technical stakeholders understand complex software structures.

The name "C4" stands for Context, Containers, Components, and Code, which correspond to four levels of architectural diagrams that progressively zoom into the system:

  1. Context Diagram
    Shows the system in its environment, including users, external systems, and how they interact with it. It answers the question: What is the system and who uses it?

  2. Container Diagram
    Breaks down the system into high-level technology containers (applications, databases, services, etc.) and shows how these containers communicate. It answers: What are the major building blocks of the system?

  3. Component Diagram
    Focuses inside a container to show components (modules, services, classes) and their relationships. It answers: How is a container structured internally?

  4. Code Diagram
    Shows detailed design at the code level, such as classes, interfaces, or functions. This level is optional and typically created only when necessary.

Benefits of the C4 Model

  • Clarity and Simplicity
    The C4 Model uses a clear hierarchy of diagrams, making it easy to start from a high-level overview and progressively dive into details without overwhelming the audience.

  • Communication Across Roles
    By tailoring the diagram level to the audience (e.g., business stakeholders vs. developers), the C4 Model facilitates effective communication between technical and non-technical teams.

  • Technology-agnostic
    The model focuses on architectural elements and their relationships without being tied to specific technologies, enabling flexible usage across projects and tech stacks.

  • Scalability
    Suitable for systems of any size, from small applications to large-scale distributed systems.

  • Promotes Documentation Best Practices
    Encourages maintaining up-to-date, standardized architecture documentation that evolves with the system.

  • Supports Agile and Iterative Development
    Lightweight and easy to update, which fits well with agile workflows and continuous delivery environments.

Tools

We use online tool https://excalidraw.com/. You can download "scene" and import in excalidraw to edit prepared C4 Models.

Summary

The C4 Model is a structured yet simple way to visualize software architecture, providing multiple abstraction levels that help teams understand, communicate, and maintain complex systems effectively.