E-Mail Killer

Slack’s slick messaging software has convinced companies of all sizes they can move past the inbox. But is what comes next better—or worse?

People ask two questions about Slack, the interoffice chat software used by some of the world’s most closely watched companies. The first is whether the 21-month-old startup is actually worth its $2.8 billion valuation. The second is whether Slack is changing how much of the world works.

The first question is easier to answer. Even in an economy that has minted at least 65 new startups valued at $1 billion since January, Slack is growing fast. More than 1.7 million people have become daily users of the service since it was first released in February 2014; there were 10 times as many people using Slack in August of this year as there were during the same time last year. Venture-capital darlings Airbnb, BuzzFeed and Blue Bottle Coffee use it. So do Fortune 500 firms like Comcast and Walmart. Teams at NASA and the State Department are on Slack. (More than 2,000 people use Slack at Time Inc., which publishes this magazine and many others.) Not in a generation has a new tool been adopted more quickly by a wider variety of businesses or with such joy.

If you’ve used Facebook or Twitter, you’ll understand why Slack is hot. The program–it’s not that different from the instant messengers that were popular on the early Internet–helps different parts of a company communicate in real time. Slack preserves every comment in one easily searchable archive, and all those messages now skip your dreaded inbox. Slack’s users, on average, spend 10 hours each weekday plugged into the application, which means for those who are already on it, getting work done increasingly looks like being in Slack.

Which brings us to the second, harder question: Is Slack changing work, or is Slack exploding because work is changing?

A large part of what makes Slack better than email is how fluid its conversations are. The program–for which companies pay $6.67 to $12.50 per month per user–allows different parts of a business to set up different channels for discussions. In this channel, the information technology group talks. In that channel, marketing meets. Anytime someone wants to alert you to something, he or she tags your name to a message, just as on Facebook. You can follow your colleagues’ exchanges in real time, or you can come back to that conversation later.

Slack’s makers say this kind of software enables transparency. If you are not copied on an email or not included in a meeting, you might not have a clue why a decision was made. This can breed resentment and confusion. Slack lets people who might have been forgotten or ignored look back and see why or how something happened. “The current modes of communication are outdated, and there’s an opportunity for a new thing,” says John O’Farrell, a Slack board member and partner at the venture-capital firm Andreessen Horowitz.

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