Quadcap Embeddable Database 3.4

QED is a pure Java database that features:

Pure Java: a high performance, small footprint, zero-administration database, perfect for embedding with your application.
A full set of RDBMS features: transactions, data integrity, failure recovery, comprehensive SQL 92 conformance plus many SQL3 features.
Support for JDBC 2.0
Open source, free software! No license fees, no restrictions!
QEDs pure Java engine provides very high performance, since database accesses can be performed locally, without the necessity of a network round trip for every operation. Conventional JDBC drivers, no matter how fast the back-end database, incur network overhead -- frequently the bottleneck in a database application. A configurable in-memory cache also helps boost performance by reducing disk operations.

QED is designed for applications which need full database functionality without administrative overhead of a typical database. Because of its small memory/disk footprint, QED can be embedded in end-user applications for which a database would otherwise not be practical.