ERD Chart
Entity Relationship Diagram Configuration
Entities
Define your database entities and their attributes. Each entity represents a table in your database schema.
Entities
Attributes
Attributes
Attributes
Attributes
Relationships
Define relationships between entities. Specify cardinality and whether the relationship is identifying or non-identifying.
Relationships
Display Settings
Free Online ERD Chart Maker
What is an ERD Chart?
An Entity Relationship Diagram (ERD) is a visual blueprint of a relational database, showing tables as entities, columns as attributes, and lines as the relationships between them. ERDs are essential for database design, helping teams align on schema structure before writing a single line of SQL. Use one when planning a new application, documenting an existing database, or communicating how your data fits together across a system.
Key Features
Entity Blocks with Attributes
Define each database table as an entity with named attributes, data types, and optional comments — exactly like a schema spec.
PK, FK, and UK Annotations
Mark primary keys, foreign keys, and unique keys directly on attributes so relationships and constraints are immediately clear.
Cardinality Notation
Set source and target cardinality per relationship — exactly one, zero or one, one or more, zero or more — using standard crow's foot symbols.
Identifying vs Non-Identifying Relationships
Distinguish whether a child entity depends on the parent for its identity, a critical distinction for correct normalization.
Flexible Layout Directions
Arrange entities top-to-bottom, left-to-right, or any orientation to fit the natural flow of your schema.
Zoom and Pan Navigation
Explore large, complex diagrams with smooth zoom and pan so no entity gets lost off-screen.
Best For
When to Use
- You are designing a new database and need to map out tables and relationships before writing SQL
- You need to communicate schema structure to developers, analysts, or stakeholders
- You are auditing or refactoring a legacy database and want a clear picture first
- You need to identify missing foreign keys or redundant tables
- You are onboarding someone to an existing system and want a single reference diagram
- You are writing technical documentation that must include a data model
Common Mistakes
- !Skipping foreign key annotations — relationship lines alone do not show which attribute carries the FK
- !Cramming every column into one diagram instead of focusing on the key attributes that define relationships
- !Leaving relationship lines unlabeled, so viewers cannot tell what the association means
- !Mixing cardinality styles mid-diagram (Chen notation circles vs. crow's foot) — pick one and stick to it
- !Not distinguishing identifying from non-identifying relationships, which changes how child records are keyed
- !Drawing many-to-many relationships directly instead of introducing the junction table that implements them
Related Tools
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SaaS Application ER Diagram Generator – Free Online 2025
Create a clear ER diagram for your SaaS application in minutes. AI-powered, free, and customizable with PK/FK, cardinalities, and layout control. Export or embed with ease.
Database ER Diagram Creator – AI ERD Tool
Create accurate ER diagrams fast with AI. The Database ER Diagram Creator builds tables, keys, and relationships. Free, customizable, and easy to export or embed.
E-commerce Database ERD Maker | Free AI ERD Tool
Design a clean E-commerce Database ERD in minutes with our free AI maker. Customize entities, PK/FK, cardinality, and layout; preview, export, and share instantly.
Best Entity Relationship Diagram Generator (Free, AI)
Build accurate ER diagrams fast with our AI entity relationship diagram generator. Free, online, customizable, and export-ready (PNG/SVG). Create, edit, and share ERDs in minutes—no design skills needed.
Templates
Start with professionally designed templates
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View All Templates
Browse the full library to find more templates tailored to your chart.