PARSEC is a parallel relativistic spectral fully explicit PIC simulation code. The transverse electric and magnetic fields are advanced with a leap frog scheme in Fourier space and Gauss’s law is used to solve for the longitudinal electric field. Particles are advanced using the leap frog method. Options for using higher order charge and current deposition/ field interpolation and spectral smoothing are available. Periodic, absorbing, reflecting and thermal bath boundaries are available, and the same Monte-Carlo binary collision package used in OSIRIS can also be used. Absorbing and periodic boundary conditions for the fields are available.