HCC is a windows program originally written by Reclamation Team; it shows formulas, techs, comps and various stats, required resources, etc.
However, formula requirements have changed since 2009. These changes are now being maintained by the community (to the database of formulas, not the executable itself).
The past few years updates were available from http://istaria.info aka Timeless Guild but the site appears to no longer be valid.
I had also started mirroring all the updates and also provided an alternative update server.
Follow instructions to install HCC and/or download/update the config.xml file, needed to switch and start using istariareference.com as the update server.