Web data has become increasingly important for social research. Countless web services are amassing an enormous wealth of data of every conceivable kind. Not least the many social network sites collect data on human behavior and human interactions on an unprecedented scale, which can shed light on any number of social phenomena. Realizing the value of this information for the general public and for social research specifically, many services have decided to make their data publicly accessible – by setting up dedicated application programming interfaces (APIs).