Ushahidi, which means “testimony” in Swahili, is a free Web-based tool for collecting, visualizing, and mapping information. It was launched in Kenya in 2008, when a disputed election caused riots to erupt across the country. The website enabled citizens to report incidents and identify safe spaces, using their mobile phones, on the geographic platforms Google Maps, Yahoo! Maps, OpenStreetMap, and Microsoft Virtual Earth, effectively building a corps of 45,000 citizen journalists; the data was aggregated and mapped for anyone who needed it. Ushahidi has since grown into an open-source platform used worldwide in times of crisis; it has proven to be a vital tool in vastly different contexts, from the 2010 earthquakes in Haiti and Chile and the 2011 earthquake and tsunami in Japan, when targeted and effective humanitarian relief was enabled by its aggregated data, to a winter storm in Washington, DC, in January 2010, when Ushahidi provided information about road blockages and available snow plows. Using Ushahidi, communities of activists, news and relief organizations, and concerned citizens can track changing information as it emerges, making nimble response possible. The platform applies the logic of crowdsourcing to crisis management and humanitarian work, creating a new paradigm for aid: victims supplying real-time, on-the-ground information to a linked global volunteer community that orchestrates appropriate relief efforts.