Claudia Aradau gave a public lecture at the National Center of Competence in Research –The Migration-Mobility Nexus on 7 December 2023. Drawing on research conducted with Lucrezia Canzutti and Sarah Perret, the paper traces the ubiquity of mess in the governance of borders and asks what it means to formulate critiques of messy borders and messy data. The lecture was followed by comments from Ola Söderström, University of Neuchâtel and discussion with the participants. The discussion focused on which technologies can be seen as dominant at borders, how to define and conceptualise mess, and what to engage with current mobilisations around datafication and, for instance, the expansion of the Eurodac database.