|Subsidiary by Comcast|
|Founder||Sean Parker, Todd Masonis and Cameron Ring|
|Justin Miller, President & CEO|
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 January 2007, 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 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 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 October 1, 2017, Plaxo notified its users that it would be shutting down the Plaxo service at the end of the day on December 31, 2017. 
Plaxo provides automatic updating of contact information. Users and their contacts store their information in the cloud on Plaxo's servers. When this information is edited by the user, the changes appear in the address books of all those who listed the account changer in their own books. Once contacts are stored in the central location, it is possible to list connections between contacts and access the address book from anywhere.
A Plaxo plug-in supports major address books including Outlook/Outlook Express, Mozilla Thunderbird, and macOS's Contacts, iOS and BlackBerry, and others can be supported through an application programming interface. Additionally, Plaxo can be maintained online.
Charging for Outlook synchronization 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 is now called Platinum Sync.
On July 19, 2011, Plaxo announced an improved iPhone app; a new BlackBerry app; a Windows Mobile app; and syncing for Android phones with an app coming out by the end of September.
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