ARTICLE Fornaroli_DGOV_2023/IDIAP Urban Crowdsourcing Platforms across the World: A Systematic Review Fornaroli, Alessandro Gatica-Perez, Daniel Citizen Sourcing Urban Crowdsourcing EXTERNAL https://publications.idiap.ch/attachments/papers/2023/Fornaroli_DGOV_2023.pdf PUBLIC ACM Digital Government: Research and Practice 2023 https://doi.org/10.1145/3603256 URL 10.1145/3603256 doi Urban crowdsourcing platforms are becoming increasingly important, especially considering the relevance of citizen-centricity in smart cities. This systematic review aims at analysing existing academic literature on urban crowdsourcing platforms to gather citizen-generated data, and shed light on the state of research and development of these tools. Studies describing data-gathering urban crowdsourcing platforms were selected following the PRISMA protocol, for a total of 30 studies, corresponding to 32 platforms. After analysing the studies at large, this review then proceeds to examine and catalogue the platforms, focusing on their location, purpose, and public data availability. While providing valuable information on existing platforms, the catalogue is subject to different types of bias, including a geographical one, which derive primarily from the chosen methodology to identify platforms worldwide. The paper also discusses the implications of such choices.