SchemaSpy

What SchemaSpy is

SchemaSpy is a free command-line application that reads database metadata and produces HTML documentation to help teams examine data models. It can generate entity-relationship diagrams from an existing database, gather structural statistics, and flag design issues such as missing indexes, implied relationships, and orphan tables. The project says it supports over a dozen databases out of the box, with other databases accessible through a JDBC driver. Reports can display statistics or export them to Excel or CSV. Teams can include documentation generation in a CI/CD workflow to keep it current; SchemaSpy reads structural information and can run against an empty database replica. It has no graphical interface and is distributed as a JAR file or Docker image. Installation requires Java, a database-specific JDBC driver, and viz.js or Graphviz for relationship diagrams. The JAR does not include JDBC drivers, while the Docker image includes drivers for MySQL, MariaDB, PostgreSQL, and jTDS for MSSQL. The generated HTML can be shared with a team or community. SchemaSpy is free, with a listed plan price of no cost.