Holger Krekel is long-term involved with the Python community. He is best known for founding the PyPy project and as a core developer of the pytest and tox testing tools. He initiated and maintains the "execnet" python-to-python project among a number of smaller tools. He regularly gives in-house and open trainings. Besides many technical talks on Python related conferences, he gave keynotes at EuroPython, Pycon Russia and Pygrunn in 2013.