MERMAID TEMPLATE

SaaS database ERD: Mermaid Template Example

Use this Mermaid ERD template to document the core entities in a SaaS product and make relationships easier to review before migration. Manage code and settings in one place, then export the result as SVG or PNG.

  • Live Mermaid preview
  • Automatic browser draft saving
  • Strict security rendering
  • Start instantly from templates

How to get started

  1. 1. Write Mermaid syntax in the Code panel.
  2. 2. Choose a diagram type and theme in Config.
  3. 3. Pan, zoom, and inspect the canvas.
  4. 4. Export as SVG or PNG, or sign in to save a project.

What you can adapt

  • Plan account and billing tables
  • Explain ownership of product data
  • Review keys and cardinality with engineers

How to use this template

  1. 1. Replace the example entities with your domain tables.
  2. 2. Mark primary and foreign keys explicitly.
  3. 3. Add only fields that help the design review.
  4. 4. Compare the diagram with the migration or schema definition.

SaaS database ERD Mermaid code

Copy this starting point, replace the labels with your own domain, and preview the result in the editor.

erDiagram
  USER ||--o{ PROJECT : owns
  PROJECT ||--o{ REVISION : keeps
  USER ||--o{ FEATURE_USAGE : consumes
  PROJECT {
    string id PK
    string ownerId
    string title
    boolean isPublic
  }
  REVISION {
    string id PK
    string projectId FK
    string code
  }

Template FAQ

What is a SaaS database ERD useful for?

It gives a shared view of accounts, projects, billing, and other entities before the schema becomes difficult to change.

Can I add more entities?

Yes. Keep the first version focused, then add related entities when they clarify ownership or cardinality.

ER tips

Mark primary and foreign keys clearly.

Use Mermaid cardinality symbols for each relationship.

erDiagram
  USER ||--o{ PROJECT : owns
  PROJECT ||--o{ REVISION : keeps
  USER ||--o{ FEATURE_USAGE : consumes
  PROJECT {
    string id PK
    string ownerId
    string title
    boolean isPublic
  }
  REVISION {
    string id PK
    string projectId FK
    string code
  }

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