C4 Model Diagrams

Overview

The C4 model, created by Simon Brown, is a hierarchical approach to software architecture diagramming. It uses four levels of abstraction — Context, Container, Component, and Code — to describe a software system at different zoom levels. The primary tooling for C4 is the Structurizr DSL, a text-based domain-specific language purpose-built for C4 modeling.

The Four Levels

Level 1: System Context

The highest level of abstraction. Shows the system under consideration and its relationships with users (actors) and other systems. Answers: "What is the system and who uses it?"

workspace {
    model {
        user = person "User" "A customer of the system."
        email = softwareSystem "Email System" "Sends transactional emails." "External"
        system = softwareSystem "My System" "Handles core business logic."