StumbleUpon Quietly Signs Up 10 Millionth User

Without making a lot of noise about it, StumbleUpon yesterday surpassed 10 million registered users. The milestone was reached upon registration of a user that goes by the name Nellzom, a 20-year old from Colombia.

So how do we know he’s mr. diez milliones?

Because a StumbleUpon community development and support employee stumbled his profile and added the words “Nellzom is officially our 10th Million user! Welcome to StumbleUpon and its beautiful community of users!”.

Thanks to our eagle-eyed reader Paul Sanchez for uhm, stumbling upon it.

Last time we covered the size of StumbleUpon’s user base was in April 2008, when it hit 5 million users and nearly five billion stumbles. It took them another 2 years to double their number of users, but of course there’s no telling how many registered users are still active on the service. Nevertheless, according to StatCounter, StumbleUpon drives more traffic to websites than Twitter, Reddit or Digg, so they must be doing something right.

For your reference: it’s been a little over a year since StumbleUpon spun off from eBay and became an independent startup again.

As the company pointed out in a recent blog post, they have since then released the web bar as well as a new version of the flagship Mozilla add-on, its URL shortener and content syndication service, a Chrome extension, a revamped ads system, a new look to their site, an iPad app, new badges, and more. In other words, they’ve been busy.

In the blog post, dated May 4, the company also shared some interesting stats:

– 118% growth rate in active users since 2009
– 5.4 billion recommendations since April 2009
– In March 2010 alone, half a billion recommendations
– StumbleUpon users stumble links 25 times a day on average
– Users of the Mozilla add-on stumble something 400 times a month on average
– Over 100,000 Facebook fans

The company can now add 10 million users to that list.

Are you one of them? Why (not)?