Apache Derby, an Apache DB subproject, is an open source relational database implemented entirely in Java and available under the Apache License, Version 2.0. Some key advantages include: Derby has a small footprint -- about 2.6 megabytes for the base engine and embedded JDBC driver. Derby is based on the Java, JDBC, and SQL standards. Index. Apache CXF. Welcome to Apache ServiceMix! Apache Aries - Index. Apache Ant - Welcome. Apache ActiveMQ ™ Apache Tomcat - Welcome! Welcome! - The Apache HTTP Server Project. Welcome to The Apache Software Foundation!