We have now a free to use web-tool to calculate thin film spectra to check out the performance of generic layer stacks and simple structures. You can find it in Coating Design and test it out. The calculations run locally in your own browser and you can export the generated spectra as txt and jpeg, and the used design as a dsg-file.
It’s not an optimization tool, but it allows you to check up to 100 layers thick structures’ spectral effect on both sides of the chosen substrate. Hopefully you’ll find it useful!