The Smart City App Hack (SCAH) brings together a global network of smart cities facing similar challenges and a common vision: to turn citizens into solutions builders, empowering them to make apps and businesses that will make for a better city. Engaged communities have found inspiration in five main themes: urban mobility, energy & emissions, shopping & retail, culture & tourism, and the collaborative city. A global, diverse team of experts has helped participants to build their app over the course of 6 months: from idea to finished product.