Matt Mullenweg started WordPress, which now powers 16 percent of the web.
Mullenweg dropped out of the University of Houston in 2004. Even then, he was so precocious that he didn't bother with their computer classes. At 20, he had already developed the beginnings of WordPress and was fielding job offers from tech companies. He dropped out to work for CNET in San Francisco, with a promise that he could continue developing his side project 15 percent of the time.
He left to found Automattic, the company behind WordPress. WordPress alone gets 140 million visits a year with a staff of just 140, and all of Automattic’s sites see nearly half a billion visitors.
Arash Ferdowsi is a co-founder of DropBox, which is now worth an estimated $4 billion.
Ferdowski dropped out of MIT in 2007 after three years at the school. He left to found DropBox, which quickly grew from a tiny startup to a service used by hundreds of millions of people.
He's currently the company's Chief Technology Officer, and became a multimillionaire at the age of 27.
Aaron Levie started enterprise software company Box, and the company could IPO at a $3 billion valuation.
When Levie was a sophomore at USC, he was bouncing ideas back and forth with Dylan Smith, a friend at Duke. A marketing class helped Levie come up with the idea that became Box.net, a cloud content management system.
An unsolicited email to Mark Cuban got them $350,000 in funding, and they haven't looked back since. The company has its eye on an IPO some time this year.
Mark Zuckerberg has built Facebook into the world's largest social network, with over a billion monthly active users.
Zuckerberg dropped out of Harvard in 2004 during his sophomore year to move to Silicon Valley and work on Facebook full time. The site was first launched from his dorm room in February of that year.
The site has grown exponentially since then, and went public in the fall of 2012 in what was the biggest tech IPO of all time at $16 billion dollars.
Twenty-year-old Stacey Ferreira turned a tweet from Richard Branson into an investment.
In 2012, Ferreira decided to drop out of NYU when she received news that Virgin Mogul Richard Branson and Jerry Murdock would be investing in her cloud-based startup, MySocialCloud.com.
Ferreira began working on the business with her brother, Scott, in high school and continued to do so during her first two years in college. When she saw a tweet from Branson asking people to “donate $2,000 to charity,” for a chance to meet the mogul in Miami two days later for "intimate cocktails," Ferreira and her brother decided to borrow the money from their parents.
They were able to meet Branson and interested him enough that he came on as an investor and later brought on Murdock.
David Karp created Tumblr, now the 9th-most visited site in the United States, despite never graduating high school.
Karp was already a product manager at UrbanBaby, an internet forum for parents, at the age of 16. He had dropped out of Bronx Science high school a year earlier in 2001 to be home schooled, and never obtained a high school diploma.
From there, he started Davidville where he built the beginnings of Tumblr. That quickly became his full-time focus, and the company's now the United States' 9th most visited web site. Karp himself is worth an estimated $200 million.
Dustin Moskovitz is one of Facebook's billionaire co-founders, and went on to start Asana
Moskovitz was an economics major at Harvard, but dropped out in 2004 to follow Mark Zuckerberg out to Silicon Valley to help build Facebook into the global giant it is today. The company turned him into a billionaire.
He left in 2008 to found Asana, a web application designed to boost employee productivity and collaboration.
Pete Cashmore founded Mashable, which attracts more than 20 million unique users each month, at age 19.
In 2012, Pete Cashmore made Time magazine's list of the 100 most influential people, and his blog web site Mashable now attracts more than 20 million unique users monthly.
As a child, Cashmore turned to the Internet to socialize due to various medical complications and even finished high school two years late due to his health. Cashmore never attended college, but launched Mashable at the age of 19.
Daniel Ek co-founded the wildly popular music streaming service Spotify at age 21.
Ek left his studies in engineering at the Royal Institute of Technology in Sweden after eight weeks in 2005, but became a millionaire just a few years later.
At the age of 14, Ek founded his first company, and applied for an engineering job at Google at age 16. Five years later, he co-founded Spotify. The company now has more than 32 million paying subscribers worldwide.
Danielle Morrill was the first employee at Twilio and named as one of the top tech people to watch by Forbes.
Morrill dropped out of college in 2007 and is well-known in the tech world as the first employee of cloud communications platform Twilio.
In 2011, she was named one of Forbes' 30 Under 30 for Social/Mobile Technology. The next year, Morrill left Twilio to start her own company, Referly, which provides tools for collecting, sharing, and tracking links across the web.
Before founding a million-dollar company, Threadless co-founder Jeffrey Kalmikoff was kicked out of one school and dropped out of another.
Kalmikoff dropped out of graphic design school in Chicago in the late '90s. He helped build t-shirt company Threadless from a side project into a million-dollar company as a co-founder and chief creative officer. He had a somewhat mixed experience with school, telling CoolHunting "I was kicked out of one school, petitioned to get back in and then dropped out, and then I dropped out of another school - and then I taught a class there!"
Threadless' model of engaging community members and soliciting designs was so successful that it became a Harvard Business School case study. Since leaving the company in 2009, Kalmikoff has spent time at Digg and SimpleGeo, and as a startup advisor.
Zach Sims started Codecademy, which has over a million users and raised more than $10 million from investors last year, including Richard Branson.
Sims dropped out of Columbia in 2011 to build Codecademy. The startup was inspired by the fact that Sims wasn't as good of a coder as classmate and co-founder Ryan Bubinski. Within just a few years it's being used in some 200 countries.
Last year, the company raised more than $10 million dollars in funding from investors including Sir Richard Branson to support its vision of making it possible for anybody to learn how to code.
At 18, Sahil Lavingia helped design Pinterest, but left a year later to launch Gumroad.
In 2011, Lavingia dropped out of his first semester at the University of Southern California to become the second employee and lead designer at Pinterest. One year after joining the company, the entrepreneur left to start his own company, Gumroad, which lets people sell anything they can share, such as a song or blog post.
The company raised $7 million in its Series A round from Kleiner Perkins. Lavingia started designing iPhone apps at the age of 14.
Ben Milne turned his payment platform from a $1,200 investment to a multi-million-dollar company by the age of 22.
A decade ago, twenty-eight-year-old Ben Milne dropped out of the University of Northern Iowa to start his first company, Elemental Designs. In 2008, he moved on to Dwolla, an online payment system that allows you to eliminate credit cards completely.
"I started college because I thought that's where I was supposed to go," Milne told Business Insider. "I applied to one college, I got in, went, and realized it wasn't for me. I had customers so I stopped going to class."
Four years after starting Dwolla, the company is moving more than $350 million.
