Plone core-developer and founder of Starzel.de, historian by education, did time on the Plone Foundation Board of Directors. Headed of Plone Training Team and wrote of the Mastering Plone Training. Project-Lead for porting Plone to Python 3. Author of plone.app.contenttypes, collective.exportimport and a bunch of other packages. Loves teaching and is fiercely dedicated to Open Source.