A hacker fare — a phrase popularized by travel site Kayak.com — is when a passenger builds their own round-trip ticket by booking two one-way tickets to and from a destination, usually on two different airlines, in order to save money.

A "hacker fare" is a travel industry term—popularized by sites like Kayak—for a flight itinerary constructed by combining two separate one-way tickets rather than booking a traditional round-trip. This often involves flying out on one airline and returning on a different one to secure the lowest possible price. For example, you might fly Delta from New York to London but return on Virgin Atlantic because their one-way return is cheaper than Delta's round-trip package. Another variation of this is "hidden-city ticketing" (or skiplagging), where you book a flight with a layover in your actual destination and simply exit the airport there, skipping the final leg because it was cheaper than a direct flight. While hacker fares can save 10% to 20%, they come with risks: if your first flight is delayed or canceled, the second airline has no obligation to rebook you because the tickets are unrelated. Additionally, you cannot check bags on a "hidden-city" flight because they will be sent to the final ticketed destination, and airlines may penalize your frequent flyer account if they catch you.