Paul Berry became the chief technology officer of the Huffington Post in 2007. He developed technical strategies that exploited the social, real-time Web as no other journalism business ever had, enabling huge growth. To this day, even those not in love with HuffPo’s editorial product swoon over its technical capabilities. Now Berry is leaving to start a “social news” business, RebelMouse, joined by HuffPo co-founders Ken Lerer and Jonah Peretti. (Disclosure: Lerer is on CJR’s Board of Overseers.) Berry will be closely watched as he seeks to push the boundaries of journalism and technology that little bit further. Emily Bell spoke to Berry in January.

What was The Huffington Post’s secret sauce?

I am really proud of our “uptime.” I’m very proud of the speed—we load a ridiculous amount on the page in any modern browser. We wouldn’t be held back by servers failing. If you architect your code from the beginning around a global content-distribution network like Akamai, and you religiously stick to that, if you have a link from the front page of Yahoo!—and it’s 4 to 5 million hits on a page per hour to one url—that should affect your servers only in a minor way. The much more difficult stuff was big events, like elections, a tsunami. Suddenly you’d have every editor, every blogger, and every commenter going crazy.

How did you manage that 2009 growth spurt?

I couldn’t have pulled off our growth if I had been limited to developers in New York and America. I was born in Mexico, and my wife is Bulgarian, and I always knew international would mean a lot to me and my career. It was such an enormous advantage to us, and it’s gonna be core to what I’m doing with RebelMouse. I made it a mission to find people who are really smart and bright. It is nice and convenient that other parts of the world are cheaper. As many ideas about how we should interact with Facebook and Twitter and commenting came from around the world as from the Soho office.

Tell us about the fabled Huffington Post dashboard for editors.

The HuffPost core DNA that I really loved was that it was not a pure technology company, but it wasn’t a pure editorial company either. It was really just tech and edit working together in the same room. We tried to treat every editor like a ninja. An editor could have a [product] idea on Monday and literally see it live Tuesday afternoon.

You should know what’s clicking, what’s coming down, what’s been there too long; that you are sending traffic to something that’s not viral, or to something incredibly viral, or to something with a horrible exit rate.

How does it feel to leave something you built from scratch?

The fun for me is building a new house where there was nothing. At some point you are moving furniture around, re-architecting. And at another point you go into cruise control. What I’m doing now is much scarier. I’m pretty sure I can do this, but it’s a lot scarier.

What’s RebelMouse?

I couldn’t be more excited. We have two founding partners, Eric Hippeau and Ken Lerer—they have a great yin and yang to them. Jonah Peretti, who is running BuzzFeed, is involved. We’ve been really good friends for a long time now—we’re guilty of doing 2 a.m. g-chats about these things. [Ex-AOL sales honcho] Greg Coleman is also involved.

So, what is it?

I am dying to describe it, and I have to stay abstract. The slogan for RebelMouse is probably going to be “You are your community.” When I follow [NPR Twitter guru] Andy Carvin, I feel like I am on the streets of Egypt. [He gives] you that directionalized mic and then adds context and flavor and opinion on the top. RebelMouse will be focused on making that something you can do and understand at scale. 

Listen to an audio podcast of the full interview below.

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Emily Bell is director of the Tow Center for Digital Journalism at the Columbia University Graduate School of Journalism, and a member of CJR's Board of Overseers.