Documenting software architecture isn’t just a formality—it’s a critical tool for communication, onboarding, and decision-making. While the C4 Model has become popular for its simplicity and developer focus, there are several other frameworks and templates, each with strengths for specific contexts.
This post breaks down the most widely used architecture documentation models, compares them, highlights real-world use cases, and provides concrete examples to help you choose the right approach for your team and project.
1. C4 Model
What is it?
A hierarchical model (Context, Container, Component, Code) for visualizing software architecture at different levels of detail.
Best For:
- Agile teams
- Developer-centric communication
- Fast onboarding
- Modern cloud-native applications
When to Use:
- When your audience includes developers, product owners, or external stakeholders who need a visual “big picture” down to component level.
- Projects where diagrams need to stay in sync with code (C4 can be generated from code in some tools).
Example:
- SaaS web app: Context diagram shows users, payment gateways, and your platform; container diagram shows API, frontend, and database; component diagram details API modules.
Drawbacks:
- Doesn’t prescribe document structure, just diagrams.
- Less focus on non-visual documentation (rationale, cross-cutting concerns).
2. 4+1 View Model
What is it?
Introduced by Philippe Kruchten, 4+1 organizes architecture into Logical, Development, Process, Physical views, plus Scenarios.
Best For:
- Large enterprise systems
- Projects with multiple stakeholder groups
- Situations where hardware, deployment, and runtime concerns matter
When to Use:
- When you need to separate “what the system does” (Logical) from “how it is deployed” (Physical), “how it is built” (Development), and “how it runs” (Process).
- Projects with non-technical and technical audiences.
Example:
- Telecom system: Logical view shows services, Development view shows microservices repos, Process view shows runtime processes/threads, Physical view maps containers to servers, Scenarios walk through call setup.
Drawbacks:
- More effort and overhead than C4.
- Can be overkill for simple systems.
3. Views and Beyond (V&B)
What is it?
A framework from the Software Engineering Institute (SEI) that focuses on describing a system from different views (Module, Component & Connector, Allocation), each tailored to stakeholder concerns.
Best For:
- Complex systems with many stakeholders (ops, QA, business, dev)
- Organizations with a culture of detailed documentation
When to Use:
- When you need to ensure every stakeholder’s concern is addressed.
- For compliance or formal architecture review processes.
Example:
- Banking platform: Module view for code structure, Connector view for service integrations, Allocation view for cloud vs. on-prem deployment.
Drawbacks:
- Heavyweight, can be too formal for agile/startup environments.
4. Arc42
What is it?
A template for comprehensive architecture documentation, combining structure (what to write) with flexibility (how to visualize).
Best For:
- Teams looking for a complete architecture documentation template
- Projects requiring thorough coverage (context, quality scenarios, cross-cutting concerns)
When to Use:
- When you want to document not only structure, but also decisions, quality attributes, and concepts.
- Good for regulated environments or projects with high turnover.
Example:
- Healthcare platform: Use Arc42 template to document system context, business goals, architecture decisions, data flow, deployment, and risks.
Drawbacks:
- Can seem overwhelming at first.
- Not diagram-focused; you must choose your own diagram styles (often used with C4).
5. ISO/IEC/IEEE 42010
What is it?
An international standard for describing architecture using viewpoints and views.
Best For:
- Organizations needing compliance with international standards
- Very large, mission-critical projects
When to Use:
- When documentation must satisfy formal regulatory, client, or industry requirements.
Example:
- Aerospace control system: Architecture documentation split into safety, security, and deployment viewpoints as per ISO 42010 guidelines.
Drawbacks:
- Very formal and generic; doesn’t provide concrete diagram or template recommendations.
- Usually implemented through other frameworks (Arc42, 4+1, etc.).
6. ADR (Architecture Decision Records)
What is it?
A lightweight way to document individual architectural or technical decisions as short markdown/text files.
Best For:
- Agile teams
- Projects where decisions evolve rapidly
- Complementing high-level documentation
When to Use:
- When you want to record the “why” behind important choices (tech stack, database, patterns).
- When you need an auditable trail of decisions for future maintainers.
Example:
- Microservices platform: Each decision (e.g., "Use Postgres instead of MySQL") gets a 1-pager with context, options, decision, consequences.
Drawbacks:
- Not a full documentation framework, but a supplement.
7. UML (Unified Modeling Language)
What is it?
A standard visual language with diagram types (class, sequence, deployment, etc.).
Best For:
- Teams needing detailed object-level diagrams
- Generating code from diagrams (and vice versa)
- Modeling at various levels of abstraction
When to Use:
- When low-level relationships, interactions, or deployment details are needed.
- When standard visual notations are required (e.g., for handover).
Example:
- Library management system: UML class diagram for book, member, loan objects; sequence diagram for the checkout process.
Drawbacks:
- Can get too detailed (“diagram for the sake of diagram”).
- Not a documentation methodology—just diagrams.
Comparison Table
| Model | Best For | Use Case Example | Overhead | Visual/Template |
|---|---|---|---|---|
| C4 | Modern, code-centric teams | SaaS/web app | Low-Med | Visual |
| 4+1 View | Multi-stakeholder, enterprise | Telecom, ERP | Medium | Visual |
| V&B (SEI) | Formal, many stakeholders | Banking, critical infra | High | Both |
| Arc42 | Thorough, template-driven | Healthcare, gov | Medium-High | Template |
| ISO 42010 | Compliance, formal review | Aerospace, defense | High | Template |
| ADR | Decision history, agility | All | Low | Text |
| UML | Object, behavior diagrams | Component, flow models | Variable | Visual |
How to Choose?
- For startups and fast-moving teams: Start with C4 for high-level clarity + ADRs for decision history.
- For large enterprises: Use 4+1 View or V&B if many stakeholders and complex concerns. Arc42 works great if you need a thorough template.
- For regulated industries: Consider ISO 42010 compliance, usually with Arc42 or V&B as the documentation base.
- For legacy systems or heavy object-oriented designs: Use UML diagrams as needed, but avoid over-documenting.
Conclusion
No one-size-fits-all. Mix and match based on project complexity, team size, compliance needs, and audience. For most modern SaaS products, a combination of C4 diagrams, a few ADRs, and lightweight templates (even Notion or Markdown) gives the right balance of clarity and speed.
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