SQL Schema Visualizer
Paste SQL DDL and instantly visualize tables, columns, primary and foreign keys as an interactive ER diagram, with exportable Mermaid output.
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What is SQL Schema Visualizer?
The SQL Schema Visualizer is a database tool that parses SQL DDL you paste in and renders an entity-relationship style view of your schema, entirely in the browser. Every table becomes a card listing columns, data types, and key flags, while foreign key references become traceable relationships you can export as a Mermaid ER diagram.
Key Benefits
- Understand an unfamiliar database in seconds instead of reading raw DDL line by line.
- Spot missing keys, inconsistent types, and orphaned references visually.
- Document your schema with a Mermaid ER diagram that lives next to your code.
- Keep proprietary schemas private since everything runs client-side.
Common Use Cases
- •Onboarding onto a legacy database with dozens of CREATE TABLE migration files.
- •Reviewing a pull request that adds new tables or foreign keys.
- •Generating ER diagrams for technical design documents and wiki pages.
- •Teaching or learning database normalization with a concrete example schema.
How to Use the SQL Schema Visualizer
- Paste your SQL: Copy CREATE TABLE statements from your migration files or database dump and paste them into the SQL input panel, or click Example to load a sample schema.
- Parse the schema: The tool instantly parses tables, columns, keys, and constraints as you type. Watch the table count and relationship count update live.
- Explore the diagram: Browse the generated table cards showing every column with its data type, key icons for primary and foreign keys, and NULL/UNIQUE flags.
- Export Mermaid: Click Copy Mermaid ER to put a ready-to-render erDiagram definition on your clipboard, then paste it into any Mermaid-compatible documentation.
Key Features
- Parses CREATE TABLE statements including inline and table-level constraints.
- Detects primary keys, foreign keys, UNIQUE, NOT NULL, DEFAULT, and AUTO_INCREMENT.
- Follows ALTER TABLE ADD FOREIGN KEY statements for out-of-line relationships.
- Generates a Mermaid ER diagram you can paste into docs, wikis, or GitHub issues.
- Handles quoted identifiers (backticks, double quotes, brackets) and SQL comments.
Frequently Asked Questions
Which SQL dialects does the visualizer support?
It parses ANSI-style DDL shared by PostgreSQL, MySQL, and SQLite: CREATE TABLE with inline or table-level PRIMARY KEY, FOREIGN KEY, and UNIQUE constraints, plus ALTER TABLE ADD FOREIGN KEY statements. Vendor-specific types pass through as written.
Does my SQL leave the browser?
No. Parsing runs entirely client-side in JavaScript. Nothing is uploaded, logged, or stored, so internal or proprietary schemas stay private.
What is the Mermaid ER export for?
Mermaid is a diagram-as-code syntax supported by GitHub, GitLab, Notion, Obsidian, and many wikis. The generated erDiagram block renders a full ER diagram wherever you paste it, perfect for documentation.
Can I visualize a schema split across multiple migration files?
Yes. Paste all statements together in one input. The parser splits on top-level semicolons, so tables and their ALTER TABLE foreign keys from different files are merged into a single diagram.