In the emerging field of data science many exciting things are happening. Through the Internet of Things, health trackers and more we are collecting all kinds of data, that allow us to learn more about the world around us than we could have ever imagined. But how do we deal with this as designers? Why would we design with data, and how can we? And what would such a design look like? During my thesis I investigated the future of human-data interfaces, and came up with the Data Design Kit: a set of tools that helps designers and their teams to design effective and efficient human centred data flow systems.