While the smart city model is seen as a means to cope with challenges cities are facing, it is often reduced to an amalgam of technologies. Citizens are seldom included in the planning process, although they hold a key position to produce and share valuable knowledge on how they use and live in the city. Digital tools offer new opportunities to improve interaction and information exchange among urban planners and citizens, which can lead to more sustainable and responsive planning. This research intends to answer the following questions: ‘what are the opportunities and limits of involving citizens in the urban planning and decision making through digital tools?’, ‘what are the barriers to harness these tools and include citizens in the planning process?’, and ‘what are the levers to change current practices?’, The aims of this research are to understand how digital technologies open new means of planning more responsive and sustainable cities and how the role of citizens, as well as the one of urban planners, are changing in this context. To explore this topic, this research follows two different approaches. The first investigation produces a catalogue of worldwide existing digital tools for participatory urban planning. These practices are analysed regarding data (collection, production, and analysis), interactions, degree of involvement of the participant, outcomes of the tool and use of the produced information in the planning process. By giving an overview of the multiplicity of tools, this approach allows to determine both the opportunities – particularly in terms of data production and exchange – and the limitations of digital tools for participation. This overview gives a new insight on the potential use of digital tools. The second approach is a detailed study of planning processes in two cities, Geneva and Singapore, to compare their practices. Interviews with practitioners and analysis of planning documents, tools and policies are the methods used to describe current procedures in these two cities. These case studies have been selected for two reasons. Firstly, it compares a technology-driven city with one that has not yet taken full advantage of technologically driven planning practices. Secondly, it allows a comparison of top-down strategies that are supported with bottom-up initiatives with citizen-centric planning strategies. This approach helps us understand the interactions among stakeholders, the limitations of the ongoing procedures, and the barriers that hinder change. Urban planning procedures vary from one city to another, but good practices and levers for change can be identified, and put forward as recommendations to improve urban planning practices. However, many challenges need to be overcome in order to achieve this. The main challenge of studying innovative digital practices is that the value of the tools is often exaggerated. The promoted benefits are not often used to their full potential. Moreover, it is difficult to identify the deficiencies of existing practices, as practitioners will hardly ever point out failings in their own methods or practices. Another shortcoming is that procedures, tools and technology are evolving at a fast pace, which requires regular updates of data.