RF-Track is a new tracking code developed at CERN for the optimization of particle accelerators, which offers outstanding flexibility and rapid simulation speed. RF-Track can simulate beams of particles with arbitrary energy, mass, and charge, even mixed, solving fully relativistic equations of motion. It can simulate the effects of space-charge forces, both in bunched and continuous-wave beams. It can transport the beams through common elements as well as through "special" ones: 1D, 2D, and 3D static or oscillating radio-frequency electromagnetic field maps (real and complex), flux concentrators, and electron coolers. It allows element overlap, and direct and indirect space-charge calculation using fast parallel algorithms. RF-Track is written in optimized and parallel C++ and uses the scripting languages Octave and Python as user interfaces. General knowledge of Octave or Python is recommended to get the best out of RF-Track.