SQL Designer
Free and Open Source ERD tool for all popular relational databases
Visual designer where you can import you database, modify it and export to SQL or JSON.
Developer ToolsFree
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About
SQL Designer is a free, browser-based tool for visually designing database schemas. Drag out tables, define columns and relationships, and get a clean entity-relationship diagram — no install, no account needed to start. Built for developers who want to plan their data model before writing migrations.