Basically, a software that helps to fit the terahertz transmission and conductivity data with the Lorentz model or drude model or drude-Lorentz model or any other material-dependent model to get various related parameters. parameters
Just a little disclaimer I am an active researcher in THz but i do not tend to do spectroscopy so my information may not be completely up to date.
As far as i am aware this is no commerical software that does this, some THz antennas setups are sold with their own software (such as the BATOP setups)
In the vast majority of cases THz still tends to be lab based research, as such each individual lab tends to have their own fitting codes they have produced themselves. One option would be for you to do this, then you would have a code working exactly like you wished. Depending on the parameters you wish to extract if you shoot me a message/email I can give you some guidance on how to achieve this :)
Alternatively i know there is a github project focusing on this, although i haven't ever tested it myself i've attatched a link here: https://github.com/THzbiophotonics/Fit-TDS