PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
solidDB - Relational Databases
MySQL - The world's most popular open source database
VistaDB - VistaDB is an all-in-one embedded database software for.Net that is completely compliant with ADO.NET providing support for the entity framework.
MariaDB - An enhanced, drop-in replacement for MySQL
EXtremeDB - EXtremeDB is an extensive database management software that is creating an impact via extracting the actionable data for the predictive insight that, in turn, values the entire infrastructure.