Google senior vice president of engineering Vic Gundotra says that Google+ has reached the 400 million user mark. Furthermore, he says the social network’s monthly active user base has crossed 100 million, between those using the main Google+ website and mobile app.

“It was only a year ago that we opened public sign-up, and we couldn’t have imagined that so many people would join in just 12 months,” Gundotra wrote. “While Google+ is all about creating a better experience across Google, it’s also a destination.”