Schemity

Schemity is a native desktop ERD tool built for software engineers who need a fast, reliable way to design and document database schemas without the friction of cloud-based tools.\ Most ERD tools are either too primitive for real-world schema work or bloated with features you never use. Schemity sits in the middle: powerful enough for complex schemas, lightweight enough to install in seconds at just 9MB.\ It connects directly to PostgreSQL, MySQL, and SQL Server, reverse-engineering your existing database into a visual diagram instantly. From there, you have full control over the canvas. Relationship lines are freely routable, tables are freely positionable, and nothing is locked behind an auto-layout algorithm you cannot override.\ Key features include offline-first architecture, plain JSON schema storage, no account or internet connection required, N:N relationship support with automatic intermediate table generation, and one-time pricing with no subscription.