About Free ER Diagram

Free ER Diagram is an online tool for developers, database administrators, product teams, and students who need to turn SQL table definitions into readable entity-relationship diagrams.

What The Tool Does

• Parses SQL CREATE TABLE statements from common relational databases.
• Detects primary keys, foreign keys, columns, comments, and table relationships.
• Generates ER diagrams in Mermaid and PlantUML formats.
• Supports manual relationships, table grouping, image export, PDF export, backups, and shareable URLs.

Editorial Focus

The site publishes practical database design guides, SQL schema examples, and diagramming tutorials. Each technical page is reviewed against the current tool behavior and includes concrete SQL or database-design decisions readers can test. The goal is to help readers document existing databases, review schema changes, and communicate database structure clearly.

We do not republish article feeds, accept paid guest posts, or create pages solely to target search terms. See the editorial policy for the review and correction process.

Implementation And Limitations

The application uses a focused CREATE TABLE parser rather than a complete database-engine grammar. Common keys and relationships are recognized, while some engine-specific expressions require manual review. The maintained parser coverage and limitations page explains exactly what the current implementation handles.

Open Project

The application source and change history are available in the Free ER Diagram GitHub repository. This provides a public way to inspect how parsing and rendering work and to report implementation issues.

How It Handles User Data

The core tool runs in the browser. SQL input is processed locally, and history is stored locally unless you choose to export or share it.

Project Contact

Questions, corrections, and article suggestions are welcome at joeshanhai@gmail.com.