Free SQL→ER diagram tool, runs in the browser, nothing uploaded
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Free browser-based tool converts SQL CREATE TABLE statements into interactive entity-relationship diagrams with no data upload.
SQL to ER Diagram is a free, open-source tool that parses CREATE TABLE and ALTER TABLE statements and renders interactive ER diagrams in the browser. It supports PostgreSQL, MySQL, SQLite, and SQL Server syntax, including primary and foreign keys and constraints. Users can drag tables, auto-arrange layouts, add notes, and export as PNG or SVG. The entire schema is encoded in the URL for sharing without backend storage. Built in plain JavaScript without frameworks at 32KB gzipped, using canvas-based rendering with viewport culling to handle hundreds of tables smoothly. The SQL parser tracks source spans to preserve formatting during edits.
What commenters are saying
Strong positive reception centered on the tool's polish and mobile usability. The creator explains key implementation details: canvas-based rendering for performance, URL-encoded schemas eliminating backend needs, and a decision to stick with JavaScript after a Rust/WASM version proved slower due to JS-WASM boundary costs. Commenters praise the codebase's simplicity and suggest potential improvements like multi-table selection and straight-line relationship options. One user notes the tool doesn't require database connectivity like DBeaver, distinguishing it as schema-only visualization. A pedantic comment argues ER diagrams require more semantic information than SQL alone provides, though others counter that tables and entities are largely interchangeable in practice.