99designs | Matt Mickiewicz, 27 San Francisco and Melbourne Provides crowdsourced design services.
AdParlor | Hussein Fazal, 29; Kristaps Ronka, 24 Toronto Creates and manages ad campaigns on Facebook.
Advantage Media Group | Adam Witty, 29 Charleston, South Carolina Publisher of business books and magazines.
AnchorFree | David Gorodyansky, 29; Eugene Malobrodsky, 29 San Francisco Makes software that provides secure Web access and thwarts government censors.
Birchbox | Hayley Barna, 27; Katia Beauchamp, 28 New York City Subscription service that gives members monthly deliveries of high-end beauty samples.
Drop the Chalk | Jen Schnidman Medbery, 27 New Orleans Makes software to track student academic performance and behavior.
Dropbox | Arash Ferdowsi, 25; Drew Houston, 28 San Francisco Provides cloud-based storage for 25 million users.
evoJets | Christopher Kelly, 28; Adriann Wanner, 28 Aspen, Colorado On-Demand priviate jet charter service.
Extreme Entrepreneurship Tour | Sheena Lindahl, 28; Arel Moodie, 27; Michael Simmons, 29 New York City Stages entrepreneurship conferences at colleges.
Foodspotting | Alexa Andrzejewski, 27; Soraya Darabi, 27; Ted Grubb, 28 San Francisco and New York City A restaurant recommendation app based on social sharing of food photos.
Freshii | Matthew Corrin, 29 Chicago A soup-and-salad restaurant chain with 50 outlets worldwide.
Gemvara | Matt Lauzon , 25 Lexington, Massachusetts An online custom-jewelry retailer.
Gianna Fair Trade | Gianna Driver, 28 San Francisco Sells fashion and home accessories made by a worldwide network of women living in urban slums and impoverished villages.
Grasshopper | Siamak Taghaddos, 29; David Hauser, 29 Boston Provides virtual phone systems to small businesses.
GroupMe | Jared Hecht, 24; Steve Martocci, 29 New York City Provides group-based text-messaging services.
Hipmunk | Adam Goldstein, 23; Steve Huffman, 27 San Francisco A clean and simple flight and hotel search site.
Ignighter | Dan Osit, 29; Kevin Owocki, 26; Adam Sachs, 28 Delhi, India, and New York City A group-dating website with more than 2 million users in India.
inDinero | Jessica Mah, 21; Andy Su, 20 San Francisco Creator of online money-management tools for small businesses.
Instagram | Kevin Systrom, 27; Mike Krieger, 25 San Francisco Photo-sharing app with sophisticated image filters.
JackThreads | Jason Ross, 30 Cleveland Online members-only shopping club for men.
Nom Nom Truck | Misa Chien, 25; Jennifer Green, 27 Los Angeles A food truck that sells Vietnamese banh-mi sandwiches.
Kairos Society | Ankur Jain, 21 Washington, D.C. Not-for-profit organization for entrepreneurial college students.
Scvngr and LevelUp | Seth Priebatsch, 22 Boston A location-aware app and a site that encourages loyalty to local businesses through discounts.
Onswipe | Jason Baptise, 25; Andres Barreto, 24; Mark Bao, 18 New York City Offers a Web publishing platform that allows users to easily migrate their content to touch-enabled devices.
Quora | Adam D’Angelo, 26; Charlie Cheever, 29 San Francisco Crowd-based question-and-answer website.
The Refine Method | Brynn Jinnett, 27 New York City A boutique fitness studio.
Sentry Centers | Christopher Kelly, 28; Ryan Simonetti, 29 New York City Provides conference and meeting spaces to corporate clients.
The Shirt by Rochelle Behrens | Rochelle Behrens, 28 Washington, D.C. Designs and manufactures women's shirts with a hidden placket that eliminates gaps.
Solben | Daniel Gomez Iniguez, 20 Monterrey, Mexico Creates alternative energy products.
Unigo | Jordan Goldman, 27 New York City Website featuring student-generated information on hundreds of U.S. colleges and universities.
No. 1 on the Inc. 5000: Meet the Fastest-Growing Company in America
A No-Nonsense Guide to Starting Up
5 Common Startup Mistakes That Will Sink You Later
Every Startup Should Focus on These 4 Things
5 Tips to Keep Your Home-Based Business Legal