DBeaver - DBeaver - Universal Database Manager and SQL Client.
PostGIS - Open source spatial database
DataGrip - Tool for SQL and databases
H2GIS - A spatial extension of the H2 database. Compliant, Solid, Tested.
HeidiSQL - HeidiSQL is a powerful and easy client for MySQL, MariaDB, Microsoft SQL Server and PostgreSQL. Open source and entirely free to use.
QGIS - QGIS is a desktop geographic information system, or GIS.