Zillow is an online listing service for single family residences, condominiums, and co-op homes. Their online platform provides home value, historical values, rental, forecast, and geographic affordability data to potential sellers, buyers, and renters. Zillow’s “Zestimate” home price index estimate algorithm is available to website visitors, with or without a Zillow account. Zillow also has the Zillow Transaction and Assessment Database (ZTRAX), a real estate database now made available to academic, non-profit, and government researchers. Data is collected from buyers, sellers, and renters using their listing platform, then pooled with data from credit bureau TransUnion, the U.S. Census Bureau, the Freddie Mac Primary Mortgage Market Survey, and the Bureau of Labor Statistics’ Employment Cost Index. This collaboration allows Zillow to provide a more comprehensive picture of the housing market than their competitors. Their home price estimate index is able to reflect the changing conditions between time periods that homes are bought and sold. This information is useful for sellers, buyers, and renters looking for a fair deal, as well as journalists, analysts, and academics.