Tackling complex urban problems requires us to examine and leverage diverse sources of information. Today, cities capture large amounts of information in real-time. Data are captured on transportation patterns, electricity and water consumption, citizen use of government services (e.g., parking meters), and even on weather events. Through open data initiatives, government agencies are making information available to citizens. In turn, citizens are building applications that exploit this information to solve local urban problems. Citizens are also building platforms where they can share information regarding government services. Information that was previously unavailable is now being used to gauge quality of services, choose services, and report illegal and unethical behaviors (e.g., requesting bribes). To the best of our knowledge, this is the first paper to examine the range of citizen applications (“citizen apps”) targeting urban issues and to address their effects on urban planning, decision-making, problem solving, and governance. We examine citizen apps that address a wide range of urban issues from those that solve public transportation challenges to those that improve the management of public utilities and services and even public safety.