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April 2026 — 5 min read

Free ERD Maker Online — Create ER Diagrams in Your Browser

An ERD maker is a tool for creating entity relationship diagrams — the standard way to visualise a relational database schema. This guide explains what to look for in a free online ERD maker, how it differs from a generic diagram tool, and how to use SQL Designer to create ER diagrams and export working SQL with no installation required.

What Is an ERD Maker?

An ERD maker (also called an ER diagram maker or ERD creator) is a tool designed specifically for drawing entity relationship diagrams. Each entity (table) is drawn as a rectangle listing its attributes (columns), and lines between entities represent relationships, with notation on each end showing cardinality — how many records on one side relate to records on the other.

Unlike a general-purpose diagramming tool, a dedicated ERD maker understands database concepts: it knows the difference between a primary key and a regular column, it can represent foreign key constraints as connection lines, and — in the best tools — it can generate a valid CREATE TABLE SQL script directly from the diagram.

ERD Maker vs. Generic Diagram Tool

Tools like draw.io and Lucidchart let you draw any shape you like, which makes them flexible general-purpose diagramming tools. But for database design, that flexibility is actually a limitation: they don't understand data types, they can't validate constraints, and they produce no SQL output. A diagram you draw in draw.io is a picture — not a schema.

A purpose-built ERD maker works differently. Every column has a type. Every relationship is a real foreign key constraint. When you're done designing, you export a SQL script you can run directly against your database. The diagram and the DDL stay in sync because they're the same thing.

What to Look for in a Free ERD Maker

• SQL-aware column types — support for INT, VARCHAR, UUID, JSONB, and other real database types
• Foreign key relationships — draw connection lines that represent actual FK constraints, not decorative arrows
• Cardinality notation — crow's foot notation showing one-to-one, one-to-many, and many-to-many relationships
• Constraint support — PRIMARY KEY, UNIQUE, NOT NULL, AUTO_INCREMENT / SERIAL
• SQL export — generate a complete CREATE TABLE DDL script, not just an image
• Genuinely free — no diagram limits, no export paywalls, no credit card required
• Browser-based — no installation, works on any device

SQL Designer — Free ERD Maker for MySQL and PostgreSQL

SQL Designer is a free online ERD maker built for relational database schema design. It supports both MySQL and PostgreSQL — choose your target database when you create a diagram, and the column type picker and SQL export adjust accordingly.

The drag-and-drop canvas lets you add tables, define columns with correct SQL types, set constraints, and draw foreign key relationships. Relationships are rendered with crow's foot notation, so cardinality is immediately visible. When you're done, export a complete CREATE TABLE script with one click.

There are no diagram limits, no SQL export paywalls, and no subscription. Create a free account and start immediately.

How to Create an ER Diagram with SQL Designer

• 1. Open the ERD maker — sign up for free and create a new diagram.
• 2. Add entities — click the canvas to add a table for each entity in your data model.
• 3. Define attributes — add columns with names, data types, and constraints (PK, UQ, NN).
• 4. Draw relationships — drag a connection from a foreign key column to the primary key it references. Crow's foot notation is applied automatically.
• 5. Export SQL — generate a complete CREATE TABLE DDL script for MySQL or PostgreSQL in one click.

You can also import an existing SQL script to generate a diagram automatically — useful when you need to visualise a schema that was built without a visual designer.

ERD Maker vs. SQL to ERD Import

If you're starting from scratch, you use the ERD maker to design your schema visually and generate SQL. If you already have a SQL script and want to see it as a diagram, you can import it — SQL Designer will parse the CREATE TABLE statements and render the tables, columns, and relationships on the canvas automatically.

Both directions — ERD to SQL and SQL to ERD — work in the same tool, with the same free account.