This book focuses on the Visa Information System (VIS): a large-scale data infrastructure interconnecting a multiplicity of state authorities that enact border security and migration management in the European Union. The VIS is embedded within a setting of pan-European IT systems that filter international mobility, identify threatening elements, hamper the travels of poor, racialized, and alienated subjects, while at the same time facilitate the circulation of those expected to generate financial and other kinds of capital. The book examines the engineering of the VIS by analyzing how it was designed before its deployment in the field of border security, and how it is maintained to ensure continuous and secure operation. It illustrates how engineering processes that render the VIS functional are not just technoscientific, but inherently political, as they (re)configure and maintain the power to govern international mobility by digital means.