Loomio - Loomio helps groups of people make decisions together, online.
Decidim - Free Open-Source participatory democracy for cities and organizations
DemocracyOS - DemocracyOS is an open source application for online decision making.
LiquidFeedback - Online voting system (german & english) for Interactive Democracy, which is used by the Pirate...
Airesis - A decision making tool for direct democracy and e-government: participate in discussions, bring your ideas, suggest solutions and vote online
GlassFrog - GlassFrog is a software to support and advance your Holacracy practice.