This dissertation investigates what are the key component of digital platforms in relation to a wider process of urban transformation. The thesis aims to contribute to an understanding of the multiple forms that digital platforms can take by focusing on alternative spatial articulation and modes of production. By systematising the various normative claims to sharing economy, in which digital platforms and makerspaces are inscribed, I analyse discourses and practices in different urban contexts. After looking at the definitions of sharing economy, digital platforms, and makerspaces as given in the literature, the thesis proposes the concept of Urban Digital Platform (UDP). A UDP is oriented to citizen participation and facilitates the exchange of goods and services at a smaller, generally urban scale: they are both of and for the city and its inhabitants. Through detailed examinations of different cases such as short-term-rent platforms, makerspaces, civic crowdfunding platforms, and care provision and mutual help platforms, I have aimed to expand existing knowledge about the relationship between media technology and the city. The empirical material has been deployed to broaden the academic and societal debates concerning digital platforms. Indeed, the relevance of such enquiries is not limited solely to the academic world, for the practices examined here might have considerable implications for wider social issues such as participation, inclusion and exclusion, and the future development of our cities more broadly.