Private company research firm PrivCo has compiled a list of the top 10 most generous buyers of private tech companies in 2012. Call it the money-is-no-object list.

According to PrivCo, Zillow was the No. 1 most generous acquirer--on average, paying more than a staggering 70 times revenue--last year. Among Zillow's acquisitions on its shopping spree: Mortech, HotPads, Buyfolio, and RentJuice. Constant Contact came in second on PrivCo's most-generous list, paying a typical revenue multiple of 65, followed by Microsoft, at 40.

Rounding out the top 10: vmare, EMC, brightcove, Bazaarvoice, Intuit, SingTel, and IBM.  

PrivCo computes revenue multiples using a purchased company's trailing 12-month sales at the time of acquisition, or most-recent fiscal year-end available, according to its own database of private company financials.

What's notable about these big spenders? 

"These top acquirers have two things in common," says Sam Hamadeh, PrivCo's chief executive. "First, they're all public companies, and they can afford to pay more than a private company acquirer like Twitter or Airbnb."

Second, he points out the list is entirely made up of so-called strategic buyers, those companies looking to buy to do something other than achieve an explicit financial return, like take out a competitor, or enter a new market, perhaps more cost-effectively than starting from scratch. He notes that strategic buyers can afford to pay a higher price because they can achieve cost savings by plugging a new product into an existing sales force or eliminating duplicate overhead, like HR and accounting.

"None of these are private-equity firms, which pay on average only one to four times the revenue and resell at a profit," Hamadeh says. Private-equity firms "are focused on reselling within three to five years at a profit so they are very disciplined about not overpaying."

You can check out the numbers in more detail: 

Top 10

The list is part of Privco's annual Top 100 Private Tech Company M&A Report.