RatePlug is a marketing system that partners loan officers with real estate agents within multiple listing services (MLS). It offers two main services: a property flyer program that automatically generates detailed flyers for new listings and open houses with accurate mortgage payment information, and an online property report and link that provides interactive housing payment and lending information directly from the MLS listing. The system aims to keep homebuyers engaged longer on listings and allows them to explore 'what if' scenarios regarding financing options. It costs real estate agents nothing additional through their local MLS and loan officers can work with an unlimited number of agents for a low annual fee.