Ask Claude to Generate Mermaid Diagrams from Your Actual Code

Understanding how a codebase fits together is hard from reading files alone. Ask Claude to read your code and produce a Mermaid diagram you can actually render and share.

"Read the models in app/Models/ and generate a Mermaid ER diagram showing all the relationships"

Claude reads the Eloquent models (or ActiveRecord, or SQLAlchemy — whatever your ORM), traces the relationships, and outputs Mermaid syntax:

erDiagram
    User ||--o{ Order : "has many"
    Order ||--|{ OrderItem : "contains"
    OrderItem }o--|| Product : "references"
    User ||--o{ Address : "has many"
    Order }o--|| Address : "ships to"

You can ask for different diagram types depending on what you need to understand:

# How requests flow through middleware and controllers
"Generate a Mermaid sequence diagram for the checkout flow"

# How classes relate to each other
"Create a Mermaid class diagram for the payment module"

# How the state machine works
"Draw a Mermaid state diagram for order status transitions"

# How the deployment pipeline works
"Read the CI config and generate a Mermaid flowchart of the pipeline stages"

The diagrams render in GitHub markdown, Notion, Confluence, VS Code preview, and dozens of other tools — just wrap the output in a mermaid code block.

This is especially useful for:

• Onboarding — generate architecture diagrams for new team members
• Documentation — create living diagrams derived from code, not memory
• Code reviews — visualize the impact of a structural change before approving
• Planning — see the current state before designing the next iteration

Code tells you what exists. Diagrams tell you how it connects — let Claude draw the map from the territory.

via Claude Code