Beekeeper Studio : Open Source cross-platform SQL Editor and Database Manager. Use Beekeeper Studio to query and manage your relational databases, like MySQL, Postgres, ...
Alembic : Alembic is a new database migrations tool, written by the author of SQLAlchemy.
sqlmap : sqlmap is an open source penetration testing tool that automates the process of detecting and exploiting SQL injection flaws and taking over of databa...
DBeaver : Free multi-platform database tool for developers, SQL programmers, database administrators and analysts. Supports all popular databases: MySQL, Postgr...
SQL Fiddle : A tool for easy online testing and sharing of database problems and their solutions.
Franchise is a lightweight but powerful SQL tool with a notebook interface.