FLEXPART is a freely available Lagrangian particle dispersion model. It is widely used for research and operational applications, in the context of atmospheric problems from mesoscale to global scale. Primarily, it is designed for ECMWF model level and GFS pressure level input data. Ports exist for several limited-area models, inter alia MM5, WRF, COSMO, ALADIN. The main developer is Andreas Stohl.