Zillow surfers and real estate listing lurkers alike know one of the online marketplace’s standout features is the Zestimate.

There was, however, the Zestimate: a "free, unbiased valuation" for 40 million houses around the US, based on a proprietary algorithm. Half the single-family homes in America suddenly had a dollar ...

That one feature, the Zestimate — a price tag that hovers over the rooftop of every home in America and estimates its worth — is what makes Zillow so irresistible to users. The aspirational ...