pynchrotron implements synchrotron emission from cooling electrons. It removes the need for GSL which was originally relied on for a quick computation of the synchrotron kernel. The code has been ported from GSL and written directly in python as well as accelerated with numba. pynchrotron also includes an astromodels (ascl:2506.019) function for direct use in 3ML (ascl:2506.018).