Zillow is a prominent provider of real estate APIs, offering developers access to extensive property data, including the popular Zestimate, which estimates property values based on various data points. The Zillow API, accessible through the RapidAPI Marketplace, allows users to query property information by geographic area or specific addresses using endpoints such as getChart, getComps, and getZestimate. To utilize the API, users must register for a Zillow Web Services ID and can then conduct searches to retrieve detailed property information, generate charts, and access recent sales data. The API predominantly returns XML data, which can be converted to JSON for easier use in applications, and sample code is available for integration with programming languages like Python, showcasing its utility in real estate projects.