Apache Derby, an Apache DB subproject, is a relational database implemented entirely in Java. Some key advantages include a small footprint ( about 2 megabytes for the base engine and embedded JDBC driver) and being based on the Java, JDBC, and SQL standards.

Derby provides an embedded JDBC driver that lets you embed Derby in any Java-based solution. It also supports the more familiar client/server mode with the Derby Network Client JDBC driver and Derby Network Server. Derby is easy to install, deploy, and use.

Derby is also distributed as IBM Cloudscape and Sun Java DB.