How Stewart Butterfield Created the “Email Killer”

Slack might sound banal in description: a software that helps groups of co-workers exchange instant messages and swap electronic files. Yet Slack is arguably one of the fastest-growing business applications of all time.

In the past year, Slack has expanded tenfold. Its 1.25 million users now include employee teams at Samsung, eBay, Pinterest, Deloitte, Harvard University, NASA’s Jet Propulsion Laboratory and the U.S. Department of State. More than half of its customers are outside the United States, and Slack has offices in Dublin, Vancouver and is looking into the possibility of establishing outposts in Melbourne and Tokyo. Last April, Slack received a new round of private investment that valued the company, which is just two years old, at $2.8 billion. It had been valued at $1.1 billion a mere six months earlier.

Judging by the number alone, Slack is on its way to taking over the world. The reason for that is simple: the application minimizes the need for email. And in a world where immediacy and convenience matter most, it’s revolutionizing the way people communicate. From casual check-ins and company-wide announcements, to newly-posted automated reports to the latest pictures from your colleague’s new baby, Slack has become the place where office workers can huddle and learn from one another. In other words, Slack is the new office water cooler—a fun place to hang out and be part of their work community.

Behind it all is Stewart Butterfield. Butterfield’s foray into the tech start-up world started in the early 2000s. Along with some friends, Butterfield was focused on creating a massively multiplayer game. But when the production of the game slowed, Butterfield was desperate to find side revenue so he could keep paying his employees. He brought up an idea for a project that he had long been toying with—a web-based service that would give people a convenient way to share photos online. This later became Flickr—a hugely successful photo-hosting site that was bought by Yahoo in 2005.

Out on his own again, Butterfield decided to funnel his efforts into something businesses might buy. He started working on a new app in 2012, and by March 2013, he and his team had enough to work with that they were using the product themselves. By August, they had polished the app enough to release it into the world. And from the very beginning to the point of launch, Slack’s biggest selling point was the fact that was—and remains—an email killer.

“Email is a horrible way to communicate within a big organization, as each new message that comes in receives equal weight in your inbox, whether it’s earth-shattering news or a notice that the coffee machine is on the fritz again,” Butterfield explained to Fast Company.

Firms that started using Slack reported that they send nearly 50 percent less email, resolving issues inside different channels on Slack instead. For example, workers save time that was once spent deleting emails like, “Does anyone want to go out for lunch today?” and can instead peek into the “lunch” channel on Slack if they’re looking for someone to grab a sandwich with.

Butterfield also explained that, over time, users even find themselves harboring affection for Slack. It creates a cheerful environment—one that’s full of quirky emojis and funny, yet poignant, GIFs. According to a recent survey conducted by the company, 80 percent of customers felt Slack had a positive influence on their workplace culture.

“An enterprise collaboration software product is not something you expect people to love,” said Bradley Horowitz to the Wall Street Journal, the vice president of streams, photos and sharing at Google, who had once worked with Butterfield. “But people actually evangelize Slack and talk about its transformative powers. Partly it’s the tone. Stewart is such a jokester, and that voice comes through in Slack—his wit and playfulness.”

In other words, Slack is much more than just an “email killer.” Whether or not Butterfield intended it, Slack has becoming an app that genuinely makes people happy. And that’s something that Butterfield believes you can’t put a price on. The most powerful brands, he says, are the ones that people don’t just love, but also identify with. When you open the app, it greets you with a welcome message like “What a day! What cannot be accomplished on such a splendid day?” Or, “You look nice today!” That kind of connection, however simple it may seem, can go a long way during the nine-to-five grind.

“It’s very, very quick for anyone who interacts with Slack to consider Slack, the entity, their friend,” Butterfield said. “Slack is playful, and that’s really a fundamental activity that’s perhaps underappreciated in mainstream culture. It’s a great basis for human interaction. Playfulness means not just silliness, but an experimental attitude. Look at the world sideways and being curious.”