CLASS-PT modifies the CLASS (ascl:1106.020) code to compute the non-linear power spectra of dark matter and biased tracers in one-loop cosmological perturbation theory, for both Gaussian and non-Gaussian initial conditions. CLASS-PT can be interfaced with the MCMC sampler MontePython (ascl:1805.027) using the (new and improved) custom-built likelihoods found here.