Jan Behrens, Axel Kistner, Andreas Nitsche, and Björn Swierczek are four Berlin-based systems developers, who have been collaborating since the early 2000s. In June 2009, the four founded the Public Software Group to release their open source collaborations. So far, the best-known PSG project is LiquidFeedback, a decision-making software for political parties and civil society organizations. Released under MIT License in September 2009, LiquidFeedback (LF) has been adopted by various parties at a local and national level, including the German, Austrian, and Italian Pirate Parties and the Italian Movement Five Star.