This document discusses smart cities and empowering citizens through open data and technology. It presents the principles of co-creation and making to help citizens understand and act in the world. Examples are given of how the CitySDK and Smart Citizen Kit can help cities share and reuse solutions by collecting, annotating, linking and distributing open city data in a standardized way. Guidelines are provided for smarter city design that engages citizens and favors interoperability through loosely coupled, reusable systems.