Available for free via Google Play, the Android app lets users create stations based on an artist, album, or playlist, and note whether they like a song or don't want to hear it again.
Spotify founder Daniel Ek--an Inc. 30 Under 30 honoree--brought the company to the U.S. in July 2011 through a deal with Warner Music. One of Europe's largest music sites, the 6-year-old service has seen exponential growth in the U.S.
Spotify now has more than 15 million active users and more than 4 million listeners on paid subscriptions, reports Tech Crunch. In September 2011 Spotify had 2 million paid subscribers, the site notes.
CAITLIN BERENS writes about business innovation and entrepreneurs. Before Inc., she worked at Billboard, SELF, and Better Homes and Gardens. She attended Drake University, and lives in Brooklyn, New York. @CaitlinBerens