Widget syndicator Clearspring Technologies is acquiring AddThis, a bookmarking and content-sharing widget maker.

When publishers place AddThis capability on their sites, readers are better able to share content they like with friends. Its absorption into Clearspring is purported to be a multi-million-dollar deal, but specifics were not given. President/CEO Jay Rappaport called the buy a "launch pad for a universal sharing service" for both publishers and consumers.

Together the pair will be able to serve over 20 billion views per month on sites like ABC, Time Magazine, Fox and MySpace. The companies estimate their reach will number 200 million unique visitors worldwide.

Clearspring disseminates and tracks widgets for major brands, including Honda, Snapple, Sprint, Disney, Washington Post and University of California, San Francisco, which used the widget syndicator to promote a campaign about dementia. Earlier this month it partnered with SplashCast, a social advertising firm, to launch a service that helps advertisers connect with social networking users.

The widget syndicator recently raised $18 million in its third round of financing, led by New Enterprise Associates and Novak Biddle Venture Partners, among others. To date, it has raise about $35 million in venture capital.