Apache Harmony is an open-source implementation of the Java SE (Standard Edition) platform. It was developed by the Apache Software Foundation to provide a free alternative to the official Java implementation. Harmony aimed to be compatible with existing Java applications while offering a modular architecture for developers. The project began in 2005 but faced challenges, including legal disputes with Oracle, which acquired Sun Microsystems, the original creator of Java. As a result, development slowed, and in 2011, the project was effectively discontinued. Despite this, Harmony contributed to discussions about open-source Java implementations and influenced future projects.