H2 (DBMS)
H2 is a relational database management system written in Java. It can be embedded in Java applications or run in the client-server mode. The disk footprint (size of the jar file) is about 1 MB.
The software is available as open source software under modified versions of the Mozilla Public License or the original Eclipse Public License. The modification of the MPL is a shorter file header and the license name.
Read more about H2 (DBMS): Main Features, Utilities, History