Virtual Interlining is Kiwi.com’s proprietary technology that combines flights from airlines which have no commercial partnership with each other. This creates route combinations that no standard flight aggregator can show because those routes require self-transfer connections not covered by any single airline. The result is access to cheaper itineraries that simply do not exist on Expedia, Google Flights, or airline websites, which is the core reason kiwi discount codes on top of these routes deliver the lowest available fares.