Diagrams are essential for explaining complex systems and processes in technical documentation. Mermaid makes it easy to create and maintain diagrams using a simple markdown-like syntax, directly in your content files.

In this post, I’ll show several examples of diagrams you can create using Mermaid.

Flowchart Example

Let’s start with a basic flowchart showing a deployment process:

flowchart TD A[Code Changes] --> B{Code Review} B -->|Approved| C[Build & Test] B -->|Rejected| A C --> D{Tests Pass?} D -->|Yes| E[Deploy to Staging] D -->|No| A E --> F{Staging Validation} F -->|Pass| G[Deploy to Production] F -->|Fail| A G --> H[Monitor]

The code to create this flowchart is surprisingly simple:

flowchart TD
    A[Code Changes] --> B{Code Review}
    B -->|Approved| C[Build & Test]
    B -->|Rejected| A
    C --> D{Tests Pass?}
    D -->|Yes| E[Deploy to Staging]
    D -->|No| A
    E --> F{Staging Validation}
    F -->|Pass| G[Deploy to Production]
    F -->|Fail| A
    G --> H[Monitor]

Sequence Diagram Example

Sequence diagrams are perfect for showing interactions between components:

sequenceDiagram participant User participant API participant DB participant Cache User->>API: Request data API->>Cache: Check if data exists alt Data in cache Cache->>API: Return cached data API->>User: Return data else Data not in cache Cache->>API: Cache miss API->>DB: Query database DB->>API: Return data API->>Cache: Store in cache API->>User: Return data end

Class Diagram Example

Class diagrams help visualize the structure of a system:

classDiagram class Server { +String hostname +String ip +int port +start() +stop() } class Application { +String name +String version +deploy() +undeploy() } class Database { +String type +String version +backup() +restore() } Application "1..*" -- "1" Server : runs on Application "1" -- "0..*" Database : uses

Gantt Chart Example

Gantt charts are useful for project planning:

gantt title DevOps Project Timeline dateFormat YYYY-MM-DD section Planning Project kickoff :a1, 2025-04-05, 3d Infrastructure design:a2, after a1, 5d section Development Set up CI pipeline :b1, after a2, 4d Create base templates:b2, after b1, 3d section Deployment Deploy to staging :c1, after b2, 2d Testing :c2, after c1, 5d Deploy to production :c3, after c2, 2d section Monitoring Set up monitoring :d1, after c3, 3d Training :d2, after d1, 4d

Tips for Using Mermaid

  1. Keep it simple: Focus on clarity rather than creating overly complex diagrams
  2. Use consistent styling: Follow the same conventions across all your diagrams
  3. Add meaningful labels: Make sure relationships and actions are clearly labeled
  4. Test your diagrams: Some complex syntax might not render correctly in all cases

Conclusion

Mermaid diagrams are a powerful way to enhance your technical documentation with visual representations that are:

  • Version controlled with your content
  • Easy to update and maintain

By integrating diagrams directly in your markdown content, you can create more comprehensive and understandable documentation for your projects.