In this paper we explore the impacts, current and potential, that new technologies have on city planning and management, comparing the different ways in which those impacts can be harnessed for either the public good, for private profit or for a mixture of both. We argue that smart technologies do not necessarily yield a positive social product, and that the openness of information (in its different levels) plays an important part in maximizing the social product of new technologies applied to urban space. In the first part, we briefly discuss urban complexity and how technology can be used to make cities readable and actionable upon. In the second part, we analyse three technological (“smart”) initiatives related to urban planning; Waze, Uber and OpenStreetMap, analysing the different processes by which information can be turned into use-value (and from there into exchange value). In the third part, we try to understand the economic process by which information is turned into capital through its restriction. We conclude by analysing the potential conflicts between the common good and the turning of information into capital, exploring some of the ways in which open data might be important in the process of making better cities.