C4 Model

The C4 Model provides a clear and consistent method for representing software architectures at different levels of abstraction. It includes four main views: context diagram, container diagram, component diagram, and class diagram. These views help to understand and communicate the structure and interactions within a system.

Use this profile to understand the building block briefly, place it in the model, and switch to the 360° assessment when needed.

Content type

Concept

Theoretical construct: explains a term, principle, or mental model.

Classification level

Structure

What organizes, connects, or makes decisions possible.

Available perspectives

Open this building block directly in an already curated view.

360°

In brief

C4 Model – in brief

The C4 Model is a notation- and tool-independent framework for making software architecture visible and discussable across several levels, from context to code.

Where does it come from?

Simon Brown created C4 to make software architecture easier for developers to read, keep consistent, and discuss together. The trigger was the problem of trying to capture large systems in a single overloaded drawing. C4 therefore organizes the description into four levels—software system, container, component, and code—while deliberately staying notation- and tool-independent.

The mental model

Think of C4 as a controlled zoom into a system. Outside is the system context with people and neighboring systems. Then come containers as executable or deployable units, then components as meaningful building blocks inside a container, and finally code as the smallest implementation layer. Supporting landscape, dynamic, and deployment diagrams help answer additional questions.

Key building blocks

Hierarchical levels

The view moves from the outside inward and separates different levels of detail.

System context

This shows the system in relation to people and neighboring systems.

Container

Executable or deployable units make the coarse internal structure visible.

Component

Within a container, meaningful building blocks and responsibilities become visible.

Code

The lowest level connects architecture to concrete classes, modules, or files.

Supporting views

Landscape, dynamic, and deployment diagrams complement the four core levels when other questions matter.

When is it useful?

C4 helps when teams need to align on architecture across reviews, documentation, onboarding, or change decisions at multiple levels of detail. It keeps the view connected from context to code and can be complemented by dynamic or deployment views. For detailed runtime behavior, operational workflows, or deep implementation questions, additional specialized models are still needed; too much detail in one diagram makes communication harder again.

C4 model website