Firebird 2.5.3 is a popular free and open source relational database. It offers lots of ANSI SQL standard features. Besides that it runs seamlessly on Windows, Linux and Unix. Firebird comes with very extensive language support and offers really high performance, which makes it a proper player on the database market.

Features

• Complete Stored Procedures and Triggers support and ACID compliant transactions

• Referential Integrity, Multi Generational Architecture

• Tiny footprint and fully featured internal language for Stored Procedures and Triggers (PSQL)

• Support for External Functions (UDFs), supports Windows, Linux, Unix

• Almost no configuration required, large user community, optional single file embedded version

• Third party tool collection, Incremental Backups

• 64-bits builds available, full cursor implementation in PSQL

• Table monitoring, connection and Transaction Triggers, Temporary Tables

Conclusion

Firebird is a very powerful RDBMS, which can handle databases, regardless of their size with very good performance. Besides that it is almost free for maintenance too.