Sqitch - Sqitch is a standalone database change management application without opinions about your database engine, development environment, or application framework.

Errbit - The open source error catcher that's Airbrake API compliant

Liquibase - Database schema change management and release automation solution.

SQLAlchemy - SQLAlchemy is the Python SQL toolkit and Object Relational Mapper that gives application developers the full power and flexibility of SQL.

Flyway - Flyway is a database migration tool.

SqlPad - Run SQL in your browser and chart the results