Programs enabling conversion of the file:
If your objective is to convert the file from HTM to the file INDD, you can use any of the applications listed. HTM to INDD conversion process in every program intended for this purpose (so-called converters) is very intuitive and everyone is able to manage converting a file.
However, bear in mind that the list may also include programs to support and work with the indicated extensions HTM and INDD - and not only converters. In such a case, you need to open the source file HTM and from the options available in the program, choose ”Save as... INDD" or "Export to INDD".