Zillow is not paying me for this and I don't pay Zillow for ranking, placement and to be advertised on their website. This is something that has seemed to come full circle when it comes to real estate agents, the way they write content on Zillow's Blog and in the way that the real estate agents regret their support of Zillow.
Zillow sells the real estate listing agent's leads back to them for a fee. If it was like Before Zillow, the real estate agents leads would come to them directly, no anymore.
Zillow obtain's their listing data from the Brokerages. It doesn't, for the most part, obtain it's real estate data from the Multiple Listing Services, which is proprietary via the Boards of Realtors.