How to Create an ER Diagram Online Free — Database Design Tool

What Is an ER Diagram?

An entity-relationship diagram (ERD) maps out your database structure visually. Entities become tables, attributes become columns, and lines between them show relationships (one-to-one, one-to-many, many-to-many). Before writing a single CREATE TABLE statement, an ERD helps you think through your data model.

How to Create an ER Diagram

1. Open the ERD Maker
2. Define entities with their attributes using text syntax
3. Specify relationships between entities (one-to-many, many-to-many)
4. The diagram renders automatically as you type
5. Export as PNG or SVG

No drag-and-drop tedium. Type your schema, see the diagram. Export without watermarks.

When to Use an ERD

• Before building a new database — plan your tables and relationships before coding migrations
• Documentation — include in technical specs so the team understands the data model
• Refactoring — visualize an existing schema to spot redundancy or missing relationships
• Code reviews — attach ERDs to pull requests that add or modify database tables
• Interviews — system design interviews often require drawing ER diagrams

Relationship Types

• One-to-one (1:1) — User has one Profile
• One-to-many (1:N) — User has many Orders
• Many-to-many (M:N) — Students enroll in many Courses, Courses have many Students (needs a junction table)

The tool renders these with standard crow's foot notation — the industry standard for database diagrams.