SQLTools++ - Home of SQLTools++
DBeaver - DBeaver - Universal Database Manager and SQL Client.
TOra - tora - TOra is an open source SQL IDE for Oracle, MySQL and PostgreSQL dbs.
DataGrip - Tool for SQL and databases
SQL Developer - Oracle SQL Developer is a free, development environment that simplifies the management of Oracle Database in both traditional and Cloud deployments.
HeidiSQL - HeidiSQL is a powerful and easy client for MySQL, MariaDB, Microsoft SQL Server and PostgreSQL. Open source and entirely free to use.