Ditras (DIary-based TRAjectory Simulator) is a framework to simulate the spatio-temporal patterns of human mobility. It operates in two steps: the generation of a mobility diary and the translation of the mobility diary into a mobility trajectory. This method fills the gap of the current generative algorithms which fail in accurately reproducing the individuals’ recurrent schedules and, at the same time, in accounting for the possibility that individuals may break the routine during periods of variable duration. This framework allows the generation of realistic spatio-temporal trajectories of human mobility, which is of fundamental importance in a wide range of applications, such as the developing of protocols for mobile ad-hoc networks or the what-if analysis in urban ecosystems.