This page lists Firebird versions reached their end-of-life and not maintained by the Firebird Project anymore. Their last official releases continue to be available for download, see the links below. Support for these versions, if required, is available from IBPhoenix.
 
Version Series Last Published Release Appeared Discontinued
v2.5 series Firebird 2.5.9 04 Oct 2010 24 Jun 2019
v2.1 series Firebird 2.1.7 18 Apr 2008 05 Dec 2014
v2.0 series Firebird 2.0.7 12 Nov 2006 12 Apr 2012
v1.5 series Firebird 1.5.6 20 Feb 2004 08 Oct 2009
v1.0 series Firebird 1.0.3 12 Mar 2002 04 Jun 2003