CrisisCommons is a global volunteer network that uses technology to help communities during crises. It was formed in 2009 and has organized over 50 CrisisCamp events in 8 countries with over 2000 volunteers. These events bring technical volunteers together to develop tools like mapping and communication apps. Major volunteer communities include Sahana, Ushahidi, OpenStreetMap and others. CrisisCommons aims to better coordinate global crisis response by volunteers and take advantage of people's spare computing resources through crowdsourcing. Keeping volunteers engaged long-term on useful local projects is a challenge.