Dressed in a bright green t-shirt with the name of his startup—Affirm—emblazoned across the chest, Levchin looks and sounds like just another idealistic Silicon Valley entrepreneur rehearsing for Demo Day. But he isn't. As the co-founder and former CTO of PayPal, Levchin is also one of the Valley's foremost experts on the payments industry. When he says he wants to overhaul banking, you should take him seriously.

After raising $45 million in venture funding, Affirm recently launched a new service called Split Pay, which lets customers pay for online purchases in installments, instead of upfront. Merchants can offer Split Pay as a payment option on their site, just as they'd offer PayPal, and then customers can sign up for the service using nothing more than their name, phone number, email, and date of birth.