Equinox is an Eclipse project that provides a certified implementation of the OSGi R4.x core framework specification. As such, Equinox is a module runtime that allows developers to implement an application as a set of "bundles" using common services and infrastructure.
Equinox started as a project to replace the original Eclipse plug-in runtime in version 3.0 of Eclipse (circa 2004). The open source project was seeded with code donated by IBM's SMF product team and further developed to meet the needs of the Eclipse community. Adaptations made at that time were fed back into the OSGi specification process with many being incorporated in the R4 release of the OSGi framework specification. Since that time Equinox has been the reference implementation for the OSGi framework specification.