Internet giant IAC has acquired Seattle's Urbanspoon, the online restaurant guide known for its slot-machine style iPhone app. The deal closed last month but was kept under wraps until being announced by IAC this morning in conjunction with its quarterly earnings.

The purchase price wasn't disclosed. It was "a compelling offer in a pretty crummy economy," said Urbanspoon co-founder Ethan Lowry this morning. More than that, he said, it made sense from a business and competitive perspective. He cited IAC's "tremendous reach."

"Being a part of IAC gives us a chance to keep growing," he said. "It is a good thing."

Urbanspoon will continue to operate as an independent brand, and it will remain in Seattle, an IAC spokeswoman said this morning. No layoffs are planned. Even though the purchase price wasn't disclosed, IAC has promised to limit itself to deals of $100 million or less. Staci Kramer of PaidContent.org estimates the price to be "in the low double-digit millions."

Lowry declined to comment on the terms of the deal, though he said the three founders were happy with the financial outcome.

"It is a strong deal and a good deal, and financially it makes sense," said the 35-year-old co-founder.

Lowry, Adam Doppelt and Patrick O'Donnell, all former Jobster employees, founded Urbanspoon in 2006 and funded the company themselves. Using an ad-based business model, Urbanspoon was already profitable before Apple started promoting the company's iPhone app in commercials, but it became even more so after that, Lowry said.

IAC said in the news release that the acquisition will enhance its collection of local Internet brands, which include Citysearch, ServiceMagic and InsiderPages. IAC also has investments in OpenTable and MerchantCircle. Urbanspoon's aggregated restaurant reviews will be integrated into IAC properties including including Citysearch and InsiderPages, the company said.

"With millions of downloads of their iPhone app, Urbanspoon has demonstrated that they can successfully distill mash-up web content and deliver it through mobile for foodies and local restaurant seekers alike," said Dinesh Moorjani , IAC senior vice president for mobile, in the news release announcing the acquisition.

Urbanspoon has attracted a large following, with more than three million visitors going to its Web site each month and more than one million "shakes" of its iPhone app every day. Asked whether IAC was more interested in the iPhone app or the Web site business, Lowry said it was a "50-50 proposition." However, he did say that the immense popularity of the iPhone app "kind of catalyzed it."

Urbanspoon had entertained other offers over the years, but he said IAC made the most sense in part because of its ownership of Citysearch. The online local city guide has been serving local restaurant ads on behalf of Urbanspoon for the past year.

Another benefit of the deal is that IAC has given the 3-person company a lot of autonomy.

"It is kind of funny because it feels like very little has changed except now we get benefits and salaries and we can file expense reports," said Lowry. "Other than that, it feels identical."