Plaxo

The company was founded by Sean Parker and two Stanford University engineering students, Todd Masonis and Cameron Ring. Rikk Carey joined Plaxo at its inception and led engineering and products for six years as Executive Vice President. Funded by venture capital including funds from Sequoia Capital, the service officially launched on November 12, 2002.

In December 2003, Plaxo was criticized by technology journalist David Coursey, who was upset about receiving a number of requests from Plaxo users to update their contact information (similar to spam email), and who wondered how the company was planning to make money from a free service that collects personal contact and network information. However, after "changes at Plaxo and discussions with the company's remaining co-founders", Coursey reversed his stance. Plaxo also responded to these issues in a section of their website.

On July 7, 2005, Plaxo announced it had struck a deal with America Online to integrate its contact management service with its AOL and AOL Instant Messenger products.

On May 7, 2007, Comcast announced that it had partnered with Plaxo in the launch of its universal communications service, SmartZone.

On August 4, 2007 Plaxo announced the public beta of a social networking service called Plaxo Pulse. The service enabled sharing of content from multiple different sources across the social web, including blogs, photos, social networking services, rating services, and others. Users can selectively share and view content according to either pre-determined categories (e.g., friends, family, business network) or customized groups. Plaxo Pulse was the first site to feature a working version of an OpenSocial container.

In May 2008, Plaxo announced that it had signed an agreement to be acquired by Comcast. The terms of the deal were not disclosed. Comcast completed its purchase of Plaxo on July 1, 2008. That month the website reported 20 million users.

In March 2010, it was announced that CEO Ben Golub would be replaced by the company’s general manager, Justin Miller.

In March 2011 Plaxo's head of product management, Preston Smalley, was named general manager; at the same time, Plaxo announced that it was exiting social networking, ending the Plaxo Pulse social networking service, and introducing a new address book updating service.

On July 30, 2009, the previously-free synchronization services for Outlook moved to Plaxo's premium (paid) service. According to Plaxo, "this change will allow us to continue to invest in the development and support of this valuable (but high-cost) feature." Existing users of the free service were offered a 20% lifetime discount on Plaxo premium. This paid service was called Platinum Sync.