2zero is your personal climate app and the officiall Klimathon app. It helps you to actively reduce your carbon footprint with the help of a CO2 calculator & multiple CO2 challenges. Become part of a Klimathon or our 2Zero community and support our Sustainability Promise. 2zero is the perfect sustainability app for a start into a CO2 neutral future. Protect the climate together, we show you how! -I would like to participate in a Klimathon. Am I in the right place?- You are absolutely right!