• by Mark Walsh  @markfwal, June 27, 2013

Gokul Rajaram, the former managing director of Google AdSense who has spent the last three years leading ad development at Facebook, has joined has joined fast-growing payments startup Square. In his new role as the company’s product engineering lead, Rajaram will lead software development for Square Register, it’s point-of-sale system for merchants.

“I’ve been fortunate to work for two mission-driven, world-changing companies, and Square’s vision and passion for helping businesses grow is inspiring,” said Rajaram, in a statement today. “I’m thrilled to join the team and help build amazing products that drive economic growth and empower local businesses around the world.”

As product director of ads at Facebook since 2010, he oversaw product development and execution of the social network’s ad products including Facebook Exchange and extending ads to mobile devices. He’s probably best known as the “godfather” of AdSense for the key part he played in developing the Google display ad network.

Square’s system for accepting debit and credit card payments via iOS and Android devices has gained rapid adoption among small businesses as well as some larger retail partners like Starbucks. Its rise as an alternative to traditional POS systems has attracted a total of $341 million from high-profile backers including Kleiner Perkins Caufiled & Byers, Sequoia Capital, Ron Conway and Esther Dyson.