Quantities is free software and released under the Gnu Public License (GPL).

Source code related to the Quantities package can be downloaded through sourceforge.net. Make sure that you have the BSUtilities package installed (or get it from the same source).

CVS snapshots of Quantity or, preferably, a SVN repository can be found also at sourceforge.net. Only the SVN repositoty is up-to-date for development after 2017.