Yu’s startup, Reliefwatch, is a cloud platform that integrates with cell phones to help health clinics in developing countries track and manage their inventories. Although altruistic in goals, the service is also a business. Reliefwatch charges NGOs for the service that tracks supplies by calling clinicians in rural locations in the developing world and taking stock of their inventory by collecting numbers entered via touch tone on a simple mobile phone. The data is digitised and stored in a cloud-based database. It has been used in Central America and in a vaccination programme in Uganda.