Yahoo says the technology will improve communications products like Yahoo Mail and Yahoo Messenger.
Yahoo has continued a major buying spree by acquiring Xobni, which offers products designed to help people keep better track of their contacts.
Terms of the deal, announced Wednesday, were not disclosed. It comes a day after Yahoo said it had bought the moviemaking app Qwiki.
Xobni, which is "inbox" spelled backwards, offers products designed to help users uncover more information about the people they have exchanged email, calls or SMS messages with in the past. It says its services can provide "a full view of each contact, complete with their photo, job title, company details, and email history — as well as updates from Facebook and Twitter."
It offers products for several platforms including Xobni, for Microsoft Outlook; Smartr Inbox, for Google's Gmail; and Smartr Contacts, for iPhone and Android devices.
The startup has been based in San Francisco but will now move to Yahoo's headquarters in Sunnyvale, California. Current Xobni customers will be able to keep using its products, Xobni said in a blog post.
It's no longer signing up new users for its paid products, however, Xobni said in an FAQ on its website.
"This acquisition will help us make improvements to Yahoo Mail, Messenger and our overall communications offering on both desktop and mobile," a Yahoo spokeswoman said in an email.
"Our inboxes are about to get a whole lot smarter," Yahoo tweeted on its corporate Twitter account.
In April, Yahoo gave its Mail app for iPad and Android tablets a major redesign, by incorporating a digital magazine-like interface that lets users flip through emails and manage messages with a swipe. The idea behind the streamlined archiving and organizational features was to "get rid of the noise," Yahoo said.
Xobni is the latest in a growing potpourri of acquisitions for Yahoo as the company strives to reinvent itself and win back users who have flocked to other Internet companies like Facebook, Twitter and Google. Other recent purchases include Alike, a local business discovery service; Astrid, a to-do app; GoPollGo, a social polling tool; Jybe, a discovery and recommendation startup; and Summly, a news summarization service.
Over the past year, Yahoo CEO Marissa Mayer has stressed the company's focus on providing enhanced products and services geared toward "daily habits" like email, finance, sports, weather and photos, particularly on mobile devices.
Last week, during the company's annual shareholder meeting, Mayer referred to the company as a large startup. "We are making investments, and are going to continue to make investments," she said.
Xobni was founded in 2006 by Adam Smith and Matt Brezina, in a dorm room at the Massachusetts Institute of Technology in Boston.
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