SchemaSpy

What SchemaSpy is

SchemaSpy is a database documentation tool that reads structural metadata from an existing database and turns it into HTML reports. Those reports can help people examine data models through entity-relationship diagrams, database statistics, and checks for design anomalies such as missing indexes, implied relationships, and orphan tables. The project supports more than a dozen databases out of the box and can work with others that provide a JDBC driver. Statistics can appear in the reports or be exported to Excel or CSV, and the generated HTML can be shared with a team or community. SchemaSpy is a standalone command-line application with no graphical interface. It is distributed as a JAR file or Docker image, and documentation generation can be included in a CI/CD workflow to keep reports current. Because it reads structural information, it can run against an empty database replica. Setup prerequisites include Java, a JDBC driver for the database engine, and viz.js or Graphviz to render relationship diagrams. The JAR package has no JDBC drivers; the Docker image includes drivers for MySQL, MariaDB, PostgreSQL, and jTDS for MSSQL. SchemaSpy is free, with a listed plan price of $0.

Who it suits

SchemaSpy suits database teams that want shareable HTML documentation, relationship diagrams, statistics, or design anomaly reports. Its command-line format and CI/CD use also suit teams that want to regenerate documentation as part of their workflow.

Limits

The free SchemaSpy plan is listed as free. The JAR package does not include JDBC drivers; the Docker image includes drivers for MySQL, MariaDB, PostgreSQL, and jTDS for MSSQL.

Getting started

1. Visit the SchemaSpy website.
2. Install Java and obtain a JDBC driver for your database engine.
3. Install viz.js or Graphviz for relationship diagram rendering.
4. Choose the JAR distribution or Docker image.
5. Run SchemaSpy from the command line against a database or empty replica.

Verdict

Choose SchemaSpy if you want free, shareable database documentation generated from metadata, with diagrams, statistics, and anomaly checks. Look elsewhere if you need a graphical interface; SchemaSpy is operated from the command line and requires setup prerequisites for database access and diagram rendering.