In our recent Social Bookmarking Faceoff, we discovered that social bookmarking site StumbleUpon actually has more users than the more hyped Currently StumbleUpon has 1,375,696 users, according to its About page. Recently announced it had reached 1 million users. I grew even more curious about StumbleUpon's success after reading the comments on a recent post of ours, where a few StumbleUpon users left almost mystical comments about the product: "I became a Stumbler in order to learn more about the world [and] it has been invaluable", noted one commenter.

To discover more about the mysterious StumbleUpon, I interviewed co-founder and Chief Architect Garrett Camp. In this post, Garrett describes StumbleUpon as a "personalized content discovery" service and outlines how it has grown to the million plus users it has today. Interestingly, he says that nearly half their user base is outside the US and more than a third are over the age of 35!

In other highlights, Garrett muses on the serendipity of SU and the "social interaction that emerges from using StumbleUpon". We also hear about StumbleUpon's future plan to become "your guide to the web, a community-based discovery tool". Finally Garrett notes a new feature called "Stumble it!" - which lets people submit and review sites without installing the SU toolbar.

Here is the full interview...

R/WW: You started out in late 2001, yet it seems like only this year that StumbleUpon has really burst onto the scene. In May this year you 'launched' after some VC money and the company also moved from Canada to Silicon Valley. What do you think was the triggering point for the success you now have - was it that launch in May, or new features on the site, or something else?

GMC: The May launch helped, but every community reaches an inflection point where it becomes bigger and more successful than initially imagined. We think that StumbleUpon reached its inflection point earlier this year.

We registered on Nov 5th, 2001 - and for the first 4 years grew slowly but steadily as we developed the toolbar and the recommendation engine. We had less than 10,000 users for our first year, but those members were very active and contributed a lot via suggestions and feedback. This was great because we were self-funded and working out of our bedrooms in Canada.

By the time we moved to San Francisco in Jan 2006, we had crossed 500,000 registered users - and shortly afterwards met our investors who very quickly saw the potential. Their investment allowed us to upgrade our infrastructure and hire a few more people (in an actual office!) and since then we've nearly tripled again. So there hasn't been any one event that triggered SU's success, its really been a persistant and incremental refinement of a system which we've used ourselves everyday.

R/WW: You're now bigger than, with 1.3 M users to' 1 M. I have to admit that surprised me when I found out, as I'd always assumed delicious was the biggest bookmarking site around. What type of users do you think StumbleUpon attracts? it seems like it's more 'mainstream' than delicious (which all the web 2.0 geeks love)...

GMC: is focused on organizing information, whereas our focus is personalized content discovery. We help people find something of interest or make a connection with someone with similar tastes.

With respect to our demographics, nearly half our user base is outside the US, more than a third over the age of 35, and they are viewing sites in every conceivable genre - from Economics to Humor, Gardening to Photography. So essentially StumbleUpon appeals to anyone who is looking to discover great new content and who wants a personalized tool that is easy to use.

People Stumbling Right Now

R/WW: StumbleUpon is a deceptively simple concept, yet it seems to have an almost philosphical meaning to some of your users. e.g. a person named Timoteo left this comment on my blog:

"[...] I became a Stumbler in order to learn more about the world, it has been invaluable. I appreciate that your site has come to my attention because I have learned something new. I will share this site with my friends to encourage them to look."

Do you get this type of comment often and if so, does it surprise you that people are so passionate about SU?

GMC: We get comments like this all the time. It's great to hear from people who find value in the serendipity of SU. People also really like the social interaction that emerges from using StumbleUpon, since it feels much different than other online communities. The ratings and reviews connect people with similar interests in a gradual and casual way, and the social networking component improves the experience even if you aren't looking for friends... it simply helps you find great sites. So although social networking isn't the primary purpose of SU, it definitely helps create a compelling and meaningful experience.

R/WW: In a previous post, we asked Joshua Schachter from delicious what he thought the difference was between his site and SU. He said:

"Delicious is about extending memory and saving things for yourselves and others. Stumbleupon is much more about surfing, like TV, or maybe Tivo."

I would think you'd be pretty happy with a comparison to Tivo, but I wondered what you think is the main difference between the two services?

GMC: is primarily an organizational tool, one to store and access your bookmarks from anywhere. It's about enhancing memory and recall. StumbleUpon is more about personalized content discovery and assisting navigation. Surfing definitely describes the experience, but it's much more interactive than channel surfing on TV. Instead of passively browsing through just a few hundred channels, you are actively improving your experience as you stumble, rate and review great sites.

R/WW: Finally, what are your future plans for StumbleUpon?

GMC: On the product side of things, we are always looking to improve the experience and the technology behind SU. In a larger sense, we want to be your guide to the web, a community-based discovery tool.

To make it easier to submit content to SU, we've recently added a web-based interface which lets you submit pages using a similar process to digg or were calling it "Stumble it!". This lets people submit and review sites without the toolbar installed, so it should increase the number and diversity of content contributors.

We also recently integrated our database of reviews on 7M websites with popular search engines, so you can see who likes the pages you've found through Google or Yahoo. This makes searching more social and meaningful, since you can now view opinions from the community during regular search activity. This is already available on Firefox, and we plan to release it to all Internet Explorer users soon :)

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