Comcast is pulling the plug on Plaxo, an address-book synchronization service that the cable giant had once imagined would become a massive social-media property.

The Plaxo service will no longer be available as of Dec. 31, 2017, at the end of the day, according to a notice on its site. Comcast said it will begin purging user data on Jan. 1, 2018.

At one point, Plaxo claimed to have more than 50 million registered accounts. The service consolidated users’ contacts across multiple sources, automatically updating information across devices and platforms. Plaxo users also could share personal info like photos, birthdays and mailing addresses.

Comcast acquired Plaxo in 2008 in a deal reportedly worth between $150 million and $170 million. “While it’s sad to say goodbye to Plaxo, we’re eager to put more focus into our expanding core products within the Xfinity family,” Plaxo said in a statement on its website.

Plaxo was founded in 2002, before Facebook was a glimmer in young Mark Zuckerberg’s eye.

Comcast had hoped to turn Plaxo into a way “to bring the social media experience to mainstream consumers,” according to a blog post by the startup’s founders at the time of the acquisition. Among the ideas floated: discovering new TV shows to watch based on friends’ recommendations and sharing photos with friends and family that they could view “online, at work, on their mobile device, or in their living room watching TV.” But Plaxo never expanded beyond being a utility for syncing contacts; Comcast also has used Plaxo’s platform to provide address-book features for email users.

Founders of Plaxo included Sean Parker, creator of Napster and Facebook’s first president. Another one of the the company’s founders, Minh Nguyen, was convicted of the 2015 murder of his ex-wife’s husband and sentenced to life in prison.

Plaxo is providing info for users on how to export their contacts on the help section of its site (at this link).