Democracy Engine, which is owned by GG&SS Alumni Foundation Board Member Jonathan Zucker, assesses 2.75% + $0.20 per transaction to cover credit card and other fees associated with processing and distributing your donations.  While exact costs vary depending on size of transaction and type of card used, this is an effectively break even fee from Democracy Engine based on their average costs across all volume.  (By comparison, PayPal would charge 2.9% + $0.20/transaction for volume at the level of the Foundation.)  This same fee is assessed on all direct donations to recipient organizations (such as the Georgetown Gilbert & Sullivan Society) which might appear on a Foundation fundraising page now and then.