Digital technologies are being harnessed to support the public-health response to COVID-19. Which technologies proved best to track, trace and contain the outbreaks? How should city governments deploy these technologies? Has the uptake of digital solutions, tools and services speed up the digital transformation in urban areas? What are the upsides and downsides of the use of such technologies? What are the main barriers (legal, ethical, privacy, organizational) a local government encounters in their implementation?