MySQL Community Edition

MySQL Community Edition is a freely downloadable version of the world's most popular open source database that is supported by an active community of open source developers and enthusiasts.

Free Open Source Mac OS X Windows Linux BSD

PostgreSQL

PostgreSQL is a powerful, open source object-relational database system. It has more than 15 years of active development and a proven architecture that has earned it a strong reputation for reliability, data integrity, and correctness.

Free Open Source Mac OS X Windows Linux BSD

MongoDB

MongoDB (from "humongous") is a scalable, high-performance, open source NoSQL database. The database is document-oriented so it manages collections of JSON-like documents.

Free Open Source Mac OS X Windows Linux BSD Web

MariaDB

MariaDB is a backward compatible, drop-in replacement of the MySQL® Database Server. It includes all major open source storage engines. The source code for MariaDB is publically available from Launchpad.

Free Open Source Windows Linux BSD

Firebird

Firebird is a relational database offering many ANSI SQL-92 features that runs on Linux, Windows, and a variety of Unix platforms.

Free Open Source Mac OS X Windows Linux

Percona Server

Percona Server is an enhanced, drop-in MySQL® replacement which has been downloaded more than 1,400,000 times. Percona Server is based on the Percona XtraDB Storage...

Free Open Source Windows Linux BSD