Firebird is an open source SQL relational database management system that runs on Linux, Windows, and a variety of Unix. The database forked from Borland's open source edition of InterBase in 2000, but since Firebird 1.5 the code has been largely rewritten.
Firebird is a fully featured and powerful RDBMS. It can handle databases from just a few KB to many Gigabytes with good performance and almost free of maintenance!
Below is a list of some of the Firebird's major features:
Full support of Stored Procedures and Triggers
Full ACID compliant transactions
Multi Generational Architecture
Very small footprint
Fully featured internal language for Stored Procedures and Triggers (PSQL)
Support for External Functions (UDFs)
Little or no need for specialized DBAs
Almost no configuration needed
Large user community
Optional single file embedded version
Dozens of third party tools
Careful writes - fast recovery, no need for transaction logs!
Many ways to access your database
Native support for all major operating systems
64bits builds available
Full cursor implementation in PSQL
Connection and Transaction Triggers