The EPCARD program virtually simulates a flight (with time resolution of 1 min) in the “quasi-real” radiation field of cosmic secondary particles. It is based on the energy spectra of neutrons, protons, photons, electrons, positrons, muons, and pions, calculated by means of the FLUKA Monte Carlo code at various altitudes in the Earth's atmosphere down to sea level, for all possible physical parameters of solar activity and geomagnetic shielding conditions. A large scale set of “fluence-to-dose” conversion coefficients is employed, to calculate dose quantities (in units of microSievert) in terms of ambient dose equivalent, H*(10), and effective dose, E. EPCARD.Net is based on the same physical algorithms as the EPCARD program, but is currently ready to process some extended physical parameters giving more precise information about flight route doses. EPCARD.Net is a completely new code which can be run on many systems such as Microsoft Windows NT/2K/XP/Vista (using both.Net and Mono runtime platform) or ‘UNIX kernel type’ operating systems like Linux, Mac OS X or Solaris (using the Mono runtime platform).