Firebird RDBMS offers ANSI SQL features & runs on Linux, Windows & several Unix platforms. Features excellent concurrency & performance & powerful stored procedure & trigger language.
More information and downloads at https://firebirdsql.org/, issue tracker is https://github.com/FirebirdSQL/firebird/issues
LAMP eGovernment Database Project offers state and local governments a free open source, web-enabled system for use in developing public information sites. You can also use this system for government-to-government systems as well.