ObjectDB is a powerful Object Database for Java. It is compact, fast, reliable and very easy to use. ObjectDB is specially designed to efficiently handle databases of various sizes, from a few KBs to hundreds of GBs, in both embedded database mode and client server mode. As a pure Java Database, ObjectDB is written entirely in Java, and it is compliant with the new Java Data Objects (JDO) standard.

ObjectDB is the easiest way to Java Data Objects (JDO). Instead of using relational databases with or without JDO mapping tools, download the free ObjectDB Java database, and in minutes you will be able to run JDO applications in your favorite Java IDE. Forget relational databases, tables, records, fields, SQL, JDBC and drivers, and start writing more effective database code using Java classes and objects!

URL: http://www.objectdb.com/
Licence: Proprietary