StumbleUpon Reaches 25M Registered Users, Plans For Global Expansion And API

CEO Garrett Camp tells me that content discovery service StumbleUpon hit 25 million registered users earlier this week, and that those users are pretty damn active — the service is now seeing 1.2 billion Stumbles a month.

For someone like me, who sees the impressive traffic that StumbleUpon can drive to an article, the growth isn’t a big surprise, but it’s worth remembering that StumbleUpon had some, uh, stumbles of its own, having been acquired by eBay and then spun out again as a separate company in April 2009. At the time, Camp says the site had about 5.5 million registered users, so that’s almost 5x growth in three years.

“If we continue at this rate, we could see hundreds of millions of users,” he says.

Last December, StumbleUpon unveiled a redesign intended to make the service more friendly to new users and to brands. Then earlier this month, it released an app that integrated with Facebook Timeline. Both changes are starting to make a difference in the company’s growth and usage, Camp says.

Looking forward, Camp tells me that StumbleUpon has three big priorities for the rest of the year. First, there’s mobile. Mobile Stumbles grew 800 percent in the past year, and the company plans to launch new, faster versions of its mobile apps soon.

Second, there’s international growth. Right now, 85 percent of StumbleUpon’s traffic comes from North America, but the company is working to translate the site, and it plans to launch in the United Kingdom, France, and Germany, with further European launches lined up after that.

Third, Camp wants to help other services access StumbleUpon’s data through an API. If you’re a content site, for example, it could be useful for your readers to see related articles that are highly recommended by StumbleUpon users. Partners beta testing the API include QQ International, VICE, and Grooveshark.

Oh, and if you’re wondering about that 25 millionth user, here’s the first page they saw through StumbleUpon.