C4 Model is the Missing Piece in Your Technical Communication Strategy
Why business leaders should care about the C4 Model: improved technical communication, faster development cycles, and fewer misunderstandings through structured architecture diagrams.
Hello everyone, and welcome back to Tech Trendsetters, where we explore the intersection of technology, innovation, and real-world business applications. I've been thinking a lot about architectural modeling lately, particularly the C4 Model. Today's episode isn't just for architects and developers. If you're leading teams that build complex software systems, this conversation directly impacts your work and results.
Today I want to share some insights about Simon Brown's C4 Model, clear up some misunderstandings, and explain why I think this approach is criminally underused in organizations that could really benefit from it.
I've sat through so many meetings, I‘ve watched over so many teams that struggle to communicate simple technical concepts – endless architecture debates that go nowhere, confusing diagrams, and business leaders pretending to understand while being completely lost.
It's a wasteful cycle that the C4 Model can break – if only people would use it properly. Today I'll walk you through what the C4 Model actually is, why it matters, and the common mistakes teams make when trying to implement it.
Why Most Architecture Diagrams Fail
Most architectural diagrams are useless. I'm not exaggerating. They're either too detailed, drowning viewers in implementation specifics, or too abstract, offering nothing of substance. The middle ground seems impossible to find.
Here we find the C4 Model. Despite what many believe, it's not some fresh-faced newcomer. It's been around since 2007. Simon Brown created it as a structured approach to creating architecture diagrams that actually make sense to different audiences. Think Google Maps. Sometimes you need to see the entire country. Other times, you need street-level details. The C4 Model is exactly that – a way to zoom in and out depending on who needs to understand what.
The model consists of four key elements:
A set of hierarchical abstractions (software systems, containers, components, and code);
A set of hierarchical diagrams that visualize these abstractions;
Notation independence;
Tooling independence;
Its popularity exploded after the pandemic when remote work exposed the fatal flaws in how teams communicate technical concepts. Suddenly, being in the same room to explain your terrible diagrams wasn't an option anymore. Teams needed something better. Something structured.
And no, it's not meant to replace UML. That's a common misunderstanding that drives me crazy. The C4 Model complements UML by providing a framework for creating meaningful diagrams. It's about telling different stories to different audiences with appropriate levels of detail.
One surprising recommendation from Simon Brown that runs counter to typical design advice: don't shy away from text. Lots of text. While most designers preach minimalism, Simon advocates for abundant text and metadata on your diagrams. Adding more text provides richer context, reducing ambiguity and guiding everyone toward a consistent understanding. Modern diagramming tools also make it easy to organize or hide additional details when needed, so you get clarity without sacrificing readability or simplicity. A diagram without sufficient explanation risks becoming just a pretty picture, interpreted differently by each viewer.
Four Levels of C4
The four levels of the C4 Model are elegant in their simplicity:
System Context – showing your system and its environment;
Container – revealing the technological components and their interactions;
Component – breaking down individual containers;
Code – diving into implementation details;
Why four levels? Why not three or five? Simon Brown believes it's critical that diagrams remain grounded in reality – specifically in components and code at the lower levels. I couldn't agree more.
Some complain that four levels is "too limiting." These people miss the entire point. The limitation is precisely what makes it valuable. Without boundaries, architectural discussions devolve into an infinite fractal mess of systems, subsystems, sub-subsystems, and so on. I only can wish a good luck making sense of that nightmare.
You still think you need more levels? Try managing an infinite hierarchy where terms become indistinguishable. Is "database" referring to the database server? A specific database instance? A particular schema? Without clear abstraction levels, these conversations go nowhere fast.
And yes, the standard blue and gray colors might seem boring. Change them if you want. That's not the hill anyone should die on. What matters is consistency and clarity, not your design sensibilities.
The model intentionally avoids additional abstractions like subsystems, bounded contexts, and layers. Simon Brown, the creator of C4, explicitly warns against these, not because they're bad concepts, but because they don't add value to the diagrams. These terms often represent organizational elements rather than true abstractions. Adding them creates unnecessary complexity that undermines the model's clarity.
Common Pitfalls using C4 Model in the Real World
The ways teams misuse the C4 Model would be comical if they weren't so damaging to productivity. Let's address some of the biggest offenders.
First, microservices. They're frequently modeled incorrectly as containers with APIs and database schemas. This approach misses the point entirely. Microservices should be modeled as software systems, containers, or groupings of containers depending on the context. As companies grow and add more teams, microservices become more complex, making proper modeling even more critical. Conway's Law here isn't just theoretical – it has real implications for how your whole company evolves.
Message-driven architectures create another common stumbling block. Don't depict a central Kafka broker as a container. Instead, represent individual topics as containers or simply label them on the arrows connecting various services. This approach provides clarity without overwhelming the diagram with unnecessary details.
The confusion between shared libraries and components is common, but they are not the same. A common mistake is depicting a shared library as a C4 container, implying it functions as an independent service. In reality, shared libraries are copied into multiple applications, not run separately. A clearer approach is to show the shared component within each application using it, with notation (e.g., color-coding) to highlight shared elements. Treating a shared library as an organizational construct helps accurately model dependencies and avoid confusion.
Context diagrams cause particular confusion when teams hand off services to separate teams. In these cases, the context diagram should show those services as distinct software systems. Internal implementation details should remain hidden behind APIs. This isn't just architectural purity – it reflects organizational reality.
We've heard many claim that they "don't use the C4 Model because they use Domain-Driven Design (DDD) instead." This statement is meaningless and reveals a fundamental misunderstanding of both approaches.
You could do your whole design process with DDD and Event Modeling and that's going to show you some aspects of the system, but ultimately you're going to have a bunch of things running on servers that's what C4 is designed for.
This way, DDD, Event Modeling and C4 aren't competitors – they're complementary tools addressing different aspects of software design. DDD focuses on modeling the problem domain; C4 addresses how to communicate and visualize software architecture. Using one doesn't preclude using the other.
Another point of contention is the naming itself. Some argue that terms like "container" and "component" aren't ideal given their other meanings in the software world. Simon acknowledges this criticism but advises against renaming them. Why? Because doing so would only create more confusion. The established terminology, despite its flaws, has achieved a level of recognition that makes renaming counterproductive. Clarity comes from consistent usage, not perfect naming.
Another key insight from the whole C4 methodology: don't try to capture architectural decisions directly on your diagrams. That's not what they're for. Document those separately using Architecture Decision Records (ADRs), and use C4 Model diagrams to complement and visualize those decisions. This separation of concerns keeps both the decisions and the visualizations clear and focused.
C4 as Code: The Future of Technical Documentation
The evolution of architectural documentation follows a clear path:
Drawing diagrams manually in tools like Miro or Visio;
Describing diagrams as code in tools like PlantUML;
Creating models in tools like Structurizr and generating multiple diagrams from a consistent model;
This shift mirrors the infrastructure-as-code revolution. Remember when we used to manually configure servers, clicking through GUI wizards and praying we could reproduce the same environment twice? Infrastructure-as-code transformed that process into something repeatable, testable, and collaborative.
C4-as-code does the same for architecture documentation.
Using C4 as code approach, we transform fragile artifacts into robust, living assets. Changes can be reviewed, versioned, and merged. The model becomes a living part of your codebase, not a stale artifact that lives in some forgotten corner of your wiki. Everyone works from the same single source of truth.
In 2022 Simon Brown demonstrated Structurizr, a tool he developed specifically for the C4 Model. You can find below a 40-minute demo showcased how a single model can generate various perspectives and views.
Scaling Large Architectures
Scaling the C4 Model for large architectures quickly becomes challenging. The complexity arises when too many elements compete for attention on the same screen. The solution isn't abandoning the model – it's creating separate diagrams for each service. Interactive diagrams help teams explore services and components dynamically, adding metadata and context where needed.
When implementing C4, focus on a single software system at a time. Avoid displaying external containers to prevent dependencies on the details of another system. A shared database can serve as a clean boundary between systems, preventing diagram creep and maintaining focus.
The power of the C4 Model isn't in pretty pictures. It's in creating a shared understanding through hierarchical abstractions and diagrams that communicate the right information to the right audience at the right level of detail.
If you're still sketching architectures on whiteboards or piecing together Miro diagrams… I can only feel sorry for you. Take a hard look at how your teams communicate technical concepts. The gap between what you think works and what actually works might actually surprise you.
Let’s embrace better modeling, let’s keep refining how we visualize software architecture, and let’s continue growing together. Until then, I wish you all the best, and I’ll see you in the next episode!
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