(Updated with initial LinkedIn response)

Xing, the Hamburg, Germany social networking site for business contacts, has just signed a deal that makes its network larger than it U.S. competitor LinkedIn.

It has announced a partnership with ZoomInfo, the largest fact-checked proprietary database in the world, of some 36 million business profiles. Xing’s two million members will now be able to search and access basic information on those profiles for free, effectively giving Xing much wider reach than LinkedIn’s 11 million members. The paperwork was signed in New York this morning, and we just got off the phone with Lars Hinrichs, Xing’s chief executive.

Xing has been putting pressure of LinkedIn for some time, having recently gone public and expanding aggressively in Europe. The accord is significant because ZoomInfo’s profiles are largely for executives in the English-speaking world, where Xing has been weak to date. [Update: However, LinkedIn has responded, saying ZoomInfo has scraped contact and other information about people without their permission, and Xing will now have to deal with privacy issues. More below.]

ZoomInfo’s profile search is the gold standard for the headhunter industry, but so far it has not been accessible without a paid membership and it has few social networking features. However, under the terms, Xing members still have to upgrade to a premium account of $5 a month in order to contact ZoomInfo people they aren’t already networked with, or to change their profiles on ZoomInfo. This is not unlike LinkedIn’s requirement that people pay for a premium membership to directly contact people not already in their network.

While Xing specializes in social networking, ZoomInfo’s value is in crawling the web, performing semantic analysis of Web pages about people, and extracting information about them to add to its database of profiles. A paying member of Xing will get full access to this information under the deal, however will not have access to most sophisticated search abilities offered by ZoomInfo. For example, while a Xing member will be able to search for a name of an IBM executive on ZoomInfo, they will not be able to search for all executives at IBM at C level. ZoomInfo effectively becomes a tool for headhunters, while Xing becomes useful for most other people.

Additionally, ZoomInfo will be launching a marketing campaign, driving its members to sign up with Xing, Hinrichs said. ZoomInfo’s 4.5 million unique monthly visitors will be able to join Xing’s network directly with a two-click process. ZoomInfo makes money from the deal from a revenue share agreement the two companies have signed.

Contact information of Xing users will continue to be protected within Xing, Hinrichs said.

We’ve sought comment from LinkedIn, and will update as necessary. [Update: LinkedIn Chairman Reid Hoffman is in transit, but did provide an initial response by email. He said “Zoominfo has scraped 36 million profiles (with lots of duplicates) and used datamining to figure out email addresses. Essentially, what this deal does, is allow Xing’s users to send email or call without permission of the people that Zoominfo has scraped…I’m not sure that this is something to crow about.”]

[Update II: Predictably, Bryan Burdick, COO of ZoomInfo, has responded to Hoffman’s criticism. He said ZoomInfo searches for information publicly available on the Web, and simply tags and organizes it so that is more useful for searchers. ZoomInfo doesn’t look behind firefalls or bot stoppers, and doesn’t license any information from third-parties. “We’re like Google,” he said. In other words, if your contact information is out there, say on your corporate Web site, it will be in ZoomInfo. ZoomInfo lets people register and add or correct information about their profiles. ZoomInfo minimizes duplicates by requiring specific information on profiles — such as name, current title, company and basic bio information. The resulting 36 million profiles is a subset of its 80 million names. Moreover, he said only 16 million of those profiles have contact information such as email address.]

Xing went public in December 2006. In March 2007, Xing acquired eConozco, a Spanish contact networks for professionals, and in May it launched a job marketplace.

The integration between Xing’s platform and ZoomInfo’s search engine will happen in fall.

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