HeidiSQL is a powerful and easy client for MySQL, MariaDB, Microsoft SQL Server and PostgreSQL. Open source and free to use.

phpMyAdmin is a free and open source tool written in PHP intended to handle the administration of MySQL or MariaDB with the use of a web browser.

SQLyog is a GUI tool for the RDBMS MySQL.

Holistics is a powerful BI platform that empowers analysts with SQL to build a data warehouse and automated reporting routines that deliver data to everyone.