LinkedIn could (eventually) make money by taking a cut of any financial transactions between parties (as Fiverr does), by charging service providers a fee to be featured more prominently in certain categories, or in a myriad of other ways. (inc.com)
Certain services may also be subject to internet service provider fees. (incrediblebank.com)
All of these are included at no charge, although third-party provider fees may apply. (mybanktracker.com)