The U.S. housing market appears to have finally bottomed out, and values are up in some of the worst-hit markets like Phoenix and Miami, Zillow Chief Executive Officer Spencer Rascoff tells CNBC.

“So five years into the housing recession and down 25 percent from the peak, we are finally at a bottom,” he tells CNBC’s “Squawk on the Street”

At this stage in the cycle, housing is very much a local story, as prices remain down in places like Atlanta and Chicago, where housing equity remains negative, he says. The trends are very much based on local employment levels and how much housing fell in each region, according to the CEO of the housing-price research website.

Still, financial analytics firm Fiserv forecasts the overall housing market won’t begin to turn the corner until next spring, according to CNNMoney.

Nationwide home prices are set to drop another 1 percent between March 2012 and March 2013, according to Fiserv’s forecast, which tracks 384 housing markets.

The next year will be choppy. Eight of the 10 markets that saw the biggest price gains over the past year are forecast to fall the most over the next year, including hard-hit Miami and Phoenix, according to Fiserv, which analyzes data from the Fiserv-Case-Shiller home price index and the Federal Housing Finance Agency.

Increased use of mobile devices by house hunters helped Zillow’s revenue surge by 75 percent in the second quarter to $27.8 million. House hunters used smartphones and tablets three times as much in the quarter as a year ago, Rascoff tells CNBC.

“To put it in perspective, a year ago, 21 homes were viewed every second on a mobile device, today it is 63 homes,” says Rascoff.

A smartphone user of Zillow is three times more likely to contact one of its premier real estate agent advertisers than a desktop Zillow user, he says.

Zillow is also developing what it projects will be the “definitive rentals marketplace” after it acquired a company that provides software tools to the rental industry. “This is huge space,” Rascoff says.