Convert F90 to SHTML

Considering that both .f90 and .html files are just specially structured text files, it should be possible to edit them in any text editor. As for actual f90 to shtml conversion, data inside these files are not related and thus cannot be successfully converted with any program.

Unfortunately, we have not found any specific information about this export this, it might be something very rare or very old or related to some long discontinued software-

Simply put, it is impossible to convert F90 to SHTML directly.
Thus, there is no so-called f90 to shtml converter or a free online .f90 to .shtml converter to be found.