We report on two state-of-the-art codes designed to characterise the spectra of late-type stars. STEPAR is a Python 3.X code that implements the EW method to calculate stellar atmospheric parameters (Teff, log(g), and [Fe/H]) of FGK stars. This code has already been extensively used to analyse high-resolution stellar spectra of thousands of Gaia-ESO Survey stars, among others. On the other hand, STEPARSYN is a Bayesian code designed to retrieve the distribution of stellar parameters of an observed spectrum using the spectral synthesis method combined with a robust scheme that rests on a Markov Chain Monte Carlo sampler.