How to convert SQL to ER diagram?

Copy your SQL CREATE TABLE statements and paste them into our free online tool. Click 'Parse All DDL' and your ER diagram will be generated instantly in PlantUML or Mermaid format.

What SQL dialects are supported?

Our tool supports MySQL, PostgreSQL, SQLite, and other SQL dialects that use CREATE TABLE syntax. It handles comments, foreign keys, auto-increment, and all common column types.

Free ER Diagram — Online SQL to ER Diagram Generator

Free ER Diagram is a free online tool that instantly converts SQL DDL (CREATE TABLE) statements into beautiful entity-relationship diagrams. No signup required, no data uploaded — everything runs locally in your browser.

Key Features

SQL DDL Parsing — Supports MySQL, PostgreSQL, SQLite and other SQL dialects. Paste your CREATE TABLE statements and parse them instantly.
PlantUML & Mermaid — Generate ER diagrams in two popular formats. Switch between them with one click.
Auto Relationship Detection — Automatically infers table relationships from FOREIGN KEY constraints.
Custom Relationships — Manually add one-to-one, one-to-many, and many-to-many relationships between tables.
Table Grouping & Partitioning — Organize tables into business modules with color-coded groups.
Export Options — Download your ER diagram as PNG image or PDF document.
Backup & Restore — Full backup of your DDL, relationships, and partitions as a JSON file.
Share via URL — Generate a shareable link that includes your complete diagram setup.
Keyboard Shortcuts — Press Ctrl/Cmd + Enter to parse all DDL instantly.

How to Use

Paste SQL DDL — Copy your CREATE TABLE statements from your database and paste them into the editor on the left panel.
Click "Parse All DDL" — Or press Ctrl/Cmd + Enter. The tool will parse your SQL and extract table structures, columns, data types, and constraints.
View ER Diagram — Your entity-relationship diagram appears on the right panel. Switch between PlantUML (remote rendering) and Mermaid (local rendering) formats.
Customize — Add custom relationships, organize tables into groups, switch between compact and detailed display modes, and choose vertical or horizontal layout.
Export — Download your diagram as PNG or PDF, or share it via a URL link.

Supported SQL Dialects

Free ER Diagram supports SQL DDL from multiple database systems including MySQL, PostgreSQL, SQLite, MariaDB, SQL Server, and Oracle. The parser handles CREATE TABLE statements with columns, data types, PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL, DEFAULT, AUTO_INCREMENT, COMMENT, and other common constraints.

Frequently Asked Questions

Is this tool really free?

Yes, completely free. No signup, no credit card, no usage limits. Just paste your SQL and generate diagrams instantly.

Is my data safe?

Absolutely. All data is processed locally in your browser. Your SQL statements are never uploaded to any server. The only external service used is PlantUML's public server for rendering PlantUML diagrams.

What is the difference between PlantUML and Mermaid?

PlantUML renders diagrams on a remote server and produces high-quality images suitable for documentation. Mermaid renders diagrams locally in your browser with interactive features and multiple theme options. Both formats are widely used in software documentation.

Can I use this for database design?

Yes! Free ER Diagram is perfect for visualizing existing database schemas, planning new databases, creating documentation, and sharing database designs with your team.