Software Architecture Diagrams with Mermaid C4
Learn how to choose a C4 level and create software architecture diagrams that explain boundaries without unnecessary detail.
By Mermaid Studio Team · Published August 2, 2026 · Updated August 2, 2026
Choose the level of detail first
Architecture diagrams fail when they mix system context, services, and implementation details in one view. C4 gives teams a vocabulary for choosing the right level for the conversation.
Start with the people and systems around your product. Add containers or components only when the audience needs to make a decision at that level.
- • Context: who uses the system and what surrounds it
- • Container: the deployable applications or data stores
- • Component: the important internal responsibilities
Create a system context diagram
Use clear names for people, systems, and external systems. Relationships should describe the interaction or dependency, not just connect two boxes.
A small Mermaid C4 context diagram
C4Context
title Project collaboration platform
Person(user, "Team member", "Creates and reviews diagrams")
System(app, "Diagram platform", "Editor, projects, and sharing")
System_Ext(auth, "Identity provider", "Authentication")
Rel(user, app, "Creates diagrams")
Rel(app, auth, "Authenticates with")Keep architecture documentation actionable
A diagram should help someone decide, operate, or change the system. Add boundaries, protocols, and ownership when they matter to that goal. Remove decorative detail that does not change the reader's understanding.
Keep the source close to the architecture documentation so a change to a service boundary can be reviewed together with the code or decision record.
Explore the architecture diagram editor
Use the architecture and C4 diagram pages as starting points, then continue in the editor when you need to adapt the system context to your own product.