ER Diagram Generator

What is ER Diagram Generator?

How does it work?

1. Define relationships as "CUSTOMER ||--o{ ORDER : places" (left entity, cardinality, right entity, label).
2. Add an attribute block per entity: type, name, and optional PK, FK or UK.
3. Choose a theme and check the rendered diagram.
4. Export SVG or PNG for schema documentation, or copy the Mermaid source.

Common use cases

• Documenting a database schema for a README or onboarding guide.
• Discussing a new data model during design review.
• Preparing an ER figure for a course assignment or thesis.
• Keeping a diagram-as-code version of the schema next to migrations.

Examples

Try this input in the tool above:

erDiagram
    CUSTOMER ||--o{ ORDER : places
    ORDER ||--|{ LINE_ITEM : contains
    PRODUCT ||--o{ LINE_ITEM : "is listed in"
    CUSTOMER {
        int id PK
        string name
        string email UK
    }
    ORDER {
        int id PK
        date created_at
        int customer_id FK
    }
    PRODUCT {
        int id PK
        string title
        float price
    }
    LINE_ITEM {
        int order_id FK
        int product_id FK
        int quantity
    }

Privacy