We are in the golden age for exoplanets studies, with currently several thousands of exoworlds discovered. Because of their low brightness and their large number, M dwarfs (~70% of stars) represent privileged targets to look for exoplanets.  By essence, those objects are also cool objects, emitting significant fraction of their light in the infrared. When detectable, exoplanets atmosphere signatures are predominantly observed in the IR, particularly for the smallest ones. It is because of those physical constrains that high-resolution spectrograph in the IR have been developed (e.g. the Spanish funded CARMENES, but also GIANO hosted in Roque de los Muchachos observatory), which science objectives are primarily driven by the detection and the characterization of exoplanets. Subsequent to the development of such cutting edge technology, raised the questions related to the optimal analysis of such exquisite data.