Home Base: Berlin
Year Founded: 2008
Power Stat: In January, the company hit the 10-million-users mark.

When SoundCloud launched, it was all about the music. Artists could upload songs and get feedback on full recordings or snippets of a track. Then they could share their work across just about every social-media outlet—and the likes of Radiohead and 50 Cent have. But as the site evolved during its three years in action, the focus has shifted. "We started seeing authors using it and politicians and news organizations," recalls cofounder Alexander Ljung. "It became clear to us that while music is super-important—it has always been super-important for humans—sound is music plus a lot more." This new mind-set, paired with a killer mobile app, makes the potential user, well, anyone. If all goes as planned, what Twitter is for words, SoundCloud will be for audio.

Why Berlin: "The city is like a big start-up. It's very much under construction. Things are changing all the time. I lived here 10 years ago, and I can feel the difference today. It's great for SoundCloud because it is such a creator-driven city." —Wahlforss

"One important spot is a café called St. Oberholz, which is where we had our office for two or three weeks. Everyone is sitting around with laptops, either planning a start-up or coding on a start-up or studying because they think they need to prepare before they start a start-up." —Ljung

What's so huge about mobile: "We introduced a mobile app with a record button—that's one single button that just allows you to capture sound wherever you are. It's a really, really simple idea. We have all gotten used to thinking about phones as a camera, but we wanted to highlight that you are walking around carrying a microphone in your pocket all the time." —Ljung

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