Wikipedia
Knopflerfish
Knopflerfish is a non-profit organization, developing OSGi related material. The project provides an easy to use open source implementation of the OSGi R4 v4.3 Core Framework and Compendium Specifications, as well as related build tools and applications. Knopflerfish is available under a BSD style license.
Knopflerfish 5, the next major release of Knopflerfish, is designed to be implemented according to the OSGi R5 specifications. A beta version of Knopflerfish has been released.