FlipKey is an online vacation rental marketplace. In 2015 it lists more than 300,000 properties in 179 countries worldwide. Its headquarters is in Boston, Massachusetts, United States. Each rental owner on the FlipKey website is verified by FlipKey staff and the site relies heavily on traveler reviews of rental properties. FlipKey also publishes ratings for travel-related items such as food blogs and in the United States it provides ratings of national historic sites.