Coruscation

Dr. Guttentag will be competing with the likes of better-established organizations, like LendingTree, Zillow Mortgage Marketplace and Bankrate.com. These so-called mortgage marketplaces have become increasingly popular as a way for borrowers to research loan rates and options. LendingTree, for example, says it has facilitated over 30 million loan requests and $214 billion in closed loan transactions since its inception 15 years ago. And all of the 1,200 mortgage-related Web sites tracked by Experian Hitwise attracted 126 million visitors in February, up 26 percent from a year ago.

The larger sites offer a mix of consumer mortgage calculators and other tools, along with rate quotes or match-ups with one or more of the hundreds of participating lenders. Many are adding other features and functions to stay more competitive.

Zillow Mortgage Marketplace has been focused on mobile applications, and the early ones have seen "tremendous usage," said Erin Lantz, the director of the marketplace. Its mobile mortgage app for the iPhone, which lets borrowers check rates and loan quotes, has been downloaded more than two million times since June. In February it began offering a version for Android phones.

LendingTree, meanwhile, plans to redesign its Web site in the next three months, and added several features, including one called "The Best Loan for Life." It will evaluate homeowners' current loans against new offerings from lenders signed up with LendingTree to see if it would be worthwhile to refinance. In June, site users will be able to add their own information -- that is, rates and terms from other lenders, not just those associated with LendingTree. This will allow them to do a side-by-side analysis "and see which one is better," said Doug Lebda, the founder.At Bankrate.com, anyone who wants to talk to a mortgage banker can now access "a call center interface" and eventually connect with a person, said Bruce Zanca, a spokesman. Not all the mortgage lenders have signed on, he said.

The Mortgage Professor's service is tiny by comparison: only six mortgage companies have signed up so far. But Dr. Guttentag said he hoped to teach the bigger shopping sites a few lessons. His mortgage shopping site consists of what he calls "certified network lenders," each of which must adhere to certain standards and post prices in real time. Borrowers may shop anonymously until they select a lender, which saves them from being bombarded with information.