This seminar will critically explore the relationships between human mobility, rights and (big) data. New sources of digital data such as mobile phones, online social networks and sensors including satellites and drones are coming together with biometric registration practices to provide an unprecedented level of detail in the surveillance of migrants, both regular and undocumented. The new data sources are facilitating an informal, often opportunistic set of practices on the part of technology experts where what are effectively mashups of migrants’ digital traces and communications are being continually created, used and shared by both nonprofit and private-sector data analysts, facilitated by discourses of humanitarian action, migration control and innovation. To make them actionable, algorithmic methods of analysis and new data infrastructures are being employed. I will argue that if we bring the analytical toolkit of Critical Data Studies to bear on these practices, we will find entirely new actors entering the field of migration control, often unwittingly – and we may gain insights into how to read and engage with the current policy landscape.