|Created by||Garrett Camp & Geoff Smith|
|Alexa rank||144 (August 2012[update])|
StumbleUpon is a discovery engine (a form of web search engine) that finds and recommends web content to its users. Its features allow users to discover and rate Web pages, photos, and videos that are personalized to their tastes and interests using peer-sourcing and social-networking principles.
StumbleUpon was founded in November 2001 by Garrett Camp, Geoff Smith, Justin LaFrance and Eric Boyd during Garrett's time in post-graduate school in Calgary, Canada. The idea of creating a company was established before the content: of the five or six ideas for products, StumbleUpon was chosen. Garrett describes in a BBC interview the moment for him in which he felt the company had really taken off: "When we passed the half a million mark (in registered users), it seemed more real."
The popularity of the software attracted Silicon Valley investor Brad O'Neill to take notice of the company and assist with a move to San Francisco, as well as bringing in subsequent fund-raising totaling $1.2 million from other angel investors including Ram Shriram (Google), Mitch Kapor (Mozilla Foundation), First Round Capital, and Ron Conway. Garrett Camp and Geoff Smith now reside in San Francisco, where StumbleUpon is headquartered.
StumbleUpon was owned by eBay from May 2007, when it was acquired for $75 million until April 2009, when Garrett Camp, Geoff Smith and several investors bought it back. StumbleUpon is now an independent, investor-backed startup once again, with offices in San Francisco and New York City.
In September 2012, StumbleUpon released an update for its iOS app that brought the new feature "StumbleDNA," which aggregates content that is recommended for you, trending content as well as a section where you can view the activity of your StumbleUpon connections. On September 25, 2012, StumbleUpon released a redesign of its website in beta, and extended it to all users on October 24.
On January 16, 2013, StumbleUpon confirmed it had laid off 30 percent of their staff from 110 to 75 employees.
On April 29, 2013, StumbleUpon selected pay-as-you-go MaxCDN offering in order to increase web page download speed.
Service details 
StumbleUpon uses collaborative filtering (an automated process combining human opinions with machine learning of personal preference) to create virtual communities of like-minded Web surfers. Rating Web sites update a personal profile (a blog-style record of rated sites) and generate peer networks of Web surfers linked by common interest. These social networks coordinate the distribution of Web content, so that users "stumble upon" pages explicitly recommended by friends and peers. Giving a site a thumbs up results in the site being placed under the user's "favorites". Furthermore, users have the ability to stumble their personal interests like "History" or "Games".
Users rate a site by giving it a thumbs up, thumbs down selection on the StumbleUpon toolbar, and can optionally leave additional commentary on the site's review page, which also appears on the user's blog. This social content discovery approach automates the "word-of-mouth" referral of peer-approved Web sites and simplifies Web navigation.
In the settings section of Stumbleupon you can further filter the types of webpages you may come across. There are interest filters which allow you to include only content for all ages, R rated content, or X rated content. There are also content filters in which you can choose to allow stumbles with audio, video, flash, and images.
On October 24, 2011, StumbleUpon deleted years worth of user-generated content, and removed HTML blogging, standalone blog posts, and photoblogging capabilities. Additionally, all previous blog posts were converted from HTML to plain text, and all photos were deleted from previous blog posts. StumbleUpon stated, "Over time, we’ve come to realize that we are not able to support and scale a blogging platform, in addition to our recommendation engine."
Content that is "stumbled upon" is informed by user's stated preferences, the thumbs up and down of their friends, and demographic information, among other factors the company does not fully disclose.
StumbleUpon Video 
On December 13, 2006, StumbleUpon launched their StumbleVideo site at http://video.stumbleupon.com/. The new site allows users without a toolbar to "stumble" through all the videos that toolbar users have submitted and rate them using an Ajax interface. The site currently aggregates videos from CollegeHumor, DailyMotion, FunnyOrDie, Google, MetaCafe, MySpace, Vimeo and YouTube.
StumbleUpon launched a version of StumbleVideo for the Internet Channel Web browser that runs on the Wii console on February 12, 2007. This version of StumbleVideo is optimized for the Wii's smaller screen resolution and offers similar functionality to that of the original version.
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In April 2007, StumbleUpon launched the StumbleThru service, allowing users of the toolbar to stumble within sites such as YouTube, The Onion, Public Broadcasting Service and Wikipedia. According to the announcement of the feature, StumbleUpon plans on adding additional Web sites in the future.
As of June 13, 2010, sites using StumbleThru include BBC.com, Blogger, Break.com, CNN.com, Collegehumor, Flickr.com, FunnyorDie.com, Howstuffworks.com, HuffingtonPost.com, Metacafe.com, Pbs.org, PhysOrg, Rolling Stone, Scientific American, The Onion, Wikipedia, Wired.com, Wordpress, and YouTube.
The StumbleThru service allows registered users to stumble on specific sites like the ones listed above, rather than the entire Web.
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In March 2009, StumbleUpon launched Su.pr, a URL shortening service. It is primarily used to link to Twitter and Facebook statuses and updates. This service is similar to that of bit.ly and TinyURL. From March through May 2009, the su.pr service was only available to people who had received an invite code, but it is now available to all StumbleUpon users.
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Paid Discovery is StumbleUpon’s ad system. StumbleUpon’s platform lets users surf the web by Stumbling to sites that match their interests, simply by hitting a button on their browser or mobile device. With Paid Discovery, an advertiser’s URL (website, video, etc.) becomes part of that stream.
Up to 5% of all stumbles are reserved for Paid Discovery where the advertisers directly insert their web page into the user experience. This means the audience lands directly on their web pages, videos, and photos. Users can also provide feedback (thumbs up / thumbs down) on this content.
Since Paid Discovery sends visitors directly to the advertiser’s page, there’s no need to create an ad; the advertiser’s entire web page is the ad. When an ad is delivered a user, a green icon or “Sponsored” will appear in the toolbar or mobile app, denoting a paid stumble. StumbleUpon doesn’t serve typical display ad formats, such as pop-ups/interstitials, banners, etc.
Advertisers have different options for how quickly and how many users they can reach with their content, depending on their marketing objectives. Serving priority dictates the order with which their web page is considered for placement, based on available inventory.
In December 2002, StumbleUpon had 1 million users. StumbleUpon claims to have more than 10,000,000 members as of 18 May 2010. StumbleUpon said that before the end of May 2008, it would have collected its five-billionth "stumble", more than one billion of which would have taken place in 2008 alone. In August 2011, StumbleUpon reached the 25 billion stumble mark, at which point they were adding over 1 billion stumbles per month. In April 2012, StumbleUpon announced that it had over 25 million registered users of the service.
In May 2007, StumbleUpon was purchased by eBay. Early reports indicated that the company was also in talks with Google and AOL before the eBay announcement. In September 2008 eBay hired Deutsche Bank to try to sell StumbleUpon again. On April 13, 2009, founders Garrett Camp and Geoff Smith and other investors including Ram Shriram bought the company.
See also 
- "The StumbleUpon Management Team". StumbleUpon. Retrieved 2009-11-01.
- "Stumbleupon.com Site Info". Alexa Internet. Retrieved 2012-08-02.
- "StumbleUpon for Windows 8 and Windows RT". Retrieved 2013-03-16.
- "StumbleUpon for iOS". Retrieved 2011-12-29.
- "StumbleUpon on Android Market". Retrieved 2011-12-29.
- "StumbleUpon for Amazon Appstore". Retrieved 2011-12-29.
- "Interview with Garrett Camp, StumbleUpon Co-Founder". CenterNetworks. December 12, 2006. Retrieved 2009-11-01.
- "Web 2.0 wonders: StumbleUpon". BBC News. 29 March 2007. Retrieved 2009-11-01.
- "eBay Acquires StumbleUpon". Business Wire, mirrored at archive.org. 2007-05-03. Archived from the original on 2007-07-07. Retrieved 2007-11-11.
- "StumbleUpon's founders buy service back from eBay". Associated Press. 13 April 2009. Retrieved 20 July 2012.
- Ha, Anthony. September 20, 2012. "StumbleUpon Revamps iOS App With Improved Navigation, Page Previews, And ‘StumbleDNA’." http://techcrunch.com/2012/09/19/stumbleupon-revamps-ios-app/
- "StumbleUpon releases new site redesign in beta, featuring Pinterest-like stumbles and lists". The Next Web. Retrieved September 25, 2012.
- "StumbleUpon Lays Off 30% Of Staff As It Restructures Company Into A Profitable State". TechCrunch. Retrieved January 16, 2013.
- "Stumbleupon “Discovers” MaxCDN for Optimizing its Content". CDN-Advisor.com. Retrieved April 29, 2013.
- "Account Changes FAQ". Retrieved 2011-12-10.
- Ferriss, Tim. "Exclusive First Look: SU.PR – Stumble Upon’s New Traffic Builder". Fourhourworkweek.com. Retrieved 2010-06-07.
- Keizer, Gregg (2006-07-18). "StumbleUpon Launches Plug-In For Microsoft Internet Explorer". InformationWeek. Retrieved 2007-02-28.
- Tuesday, May 18th, 2010 (2010-05-18). "StumbleUpon Quietly Signs Up 10 Millionth User". TechCrunch. Retrieved 2012-11-24.
- Schonfeld, Erick (2008-04-23). "Five Million Users And Nearly Five Billion Stumbles Later". TechCrunch. Retrieved 2008-04-25.
- Arrington, Michael (2008-04-18). "eBay Acquiring StumbleUpon". Techcrunch.com. Retrieved 2011-04-03.
- Arrington, Michael (2008-09-18). "That Was Fun, But Now Ebay's Selling Off StumbleUpon". Techcrunch.com. Retrieved 2010-06-07.
- "StumbleUpon's founders buy service back from eBay". Salon.com. Retrieved 2009-04-14. "The founders, Garrett Camp and Geoff Smith, bought the company back with the help of investors including Ram Shriram of Sherpalo Ventures, Accel Partners, and August Capital, they said. Financial terms were not disclosed."
- "StumbleUpon Goes Independent; Backed by Founders and New Investors". News.prnewswire.com. 2009-04-13. Retrieved 2010-06-07.