The digitization of human mobility research data and methods can temper some shortcomings of traditional approaches, particularly when more detailed or timelier data is needed to better address policy issues. We critically review the capacity of non-traditional data sources in terms of accessibility, availability, populations covered, geographical scope, representativeness bias and sensitivity, with special regard to policy purposes. We highlight how digital traces about human mobility can assist policy-making in relation to issues such as health or the environment differently to migration policy, where digital data can lead to stereotyped categorizations, unless analysis is carefully tailored to account for people’s real needs. In a world where people move for myriad reasons and these reasons may vary quickly without being incorporated in digital traces, we encourage researchers to constantly assess if what is being measured reflects the social phenomenon that the measurement is intended to capture and avoids rendering people visible in ways that are damaging to their rights and freedoms.