The H2 Database Engine, short H2, is a program written in the Java programming language relational database management system. The system can optionally be embedded as a JAR directly in Java applications or run as a server. As interfaces for addressing the operated with the system databases SQL and JDBC are available.

H2 is available as open - source software for the Java platform. In the development of the system is a slender build and a compared to other database systems, high-speed processing in the foreground.


H2 has been developed since 2004 by Thomas Müller, a Swiss software developer who previously also Hypersonic SQL created, whose development was later continued as HSQLDB. In December 2005 H2 was first published. The name stands for " Hypersonic 2"; However, this is not a further, but a completely new development.


H2 supports a subset of the SQL standard and dominates among other referential integrity, transactions, clustering, data compression, encryption and SSL. Optionally special compatibility modes for DB2, Apache Derby, HSQLDB, Microsoft SQL Server, MySQL, Oracle or PostgreSQL are activated. On the detour via the PostgreSQL compatibility, the system can also be accessed via ODBC.

Because of the wide compatibility H2 is often used as an alternative to the enumerated database systems, such as when problems occur with the system previously selected or have a leaner system such as H2 sufficient.