What It Does: Microblogging platform
Founder: David Karp, 23
Web Site: www.tumblr.com
Based: New York
In 2005, David Karp was running his software consulting business, developing new media for big media companies. He got the idea for Tumblr after becoming captivated by a new form of blogging known as "tumblelogging" that presented material of various formats (such as text, photo, and video) in a stream. While building a tumblelog for himself, the programmer realized other fans of the form would want to use a simple tool that would allow them to create their own. So during a two-week window between consulting jobs, Karp, who first started coding when he was 11, created the first iteration of such a tool designed with speed, ease of use, and customization in mind. Launched in 2007 for general consumption, the Tumblr platform now has 1.8 million users and has landed $5.5 million in venture capital from two rounds of funding with Union Square Ventures and Spark Capital. Karp, 23, says the 10-person company is not making money yet but will be experimenting with revenue-generating features this quarter. "Goal No. 1 is growth. We're aiming this thing for a mainstream audience."