Online platforms like GlobalGiving, Kiva, Network for Good, GiveIndia, HelpArgentina, and so many more – hold the potential to transform both the quality and quantity of resources available for domestic and international development. But how far do they realize that potential? And can they really revolutionize philanthropy? Keystone’s study examines the rapidly expanding phenomenon of online philanthropy markets and details the opportunity that they have to create an informational basis for results-oriented giving that encourages greater accountability and effectiveness among social purpose organizations. The study finds that online philanthropy markets are relentless innovators, and in some cases are developing interesting new ways of ensuring greater accountability for impact to their donors, beneficiaries and other constituents. This study was funded by the Program on Philanthropy and Social Innovation and conducted by Keystone, an English NGO that works to improve the effectiveness of organizations committed to social change.