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Workplace Communication App Slack Raises $43 Million at $250 Million Valuation

"This makes it a lot tougher for anyone to acquire us," said Slack CEO Stewart Butterfield.

Slack, which makes a tool that helps teams communicate, has raised $42.75 million, it said today. The round values the company at $250 million.

Word of the new round had gotten out last night on TechCrunch, though not with that amount and the investor names.

The investors are The Social + Capital Partnership, Accel Partners and Andreessen Horowitz, along with some angels, including Yelp CEO Jeremy Stoppelman, Squarespace’s Anthony Caselena, Stripe’s John and Patrick Collison, and Gigaom founder Om Malik.

Though there are many tools that help people on teams communicate with each other, San Francisco-based Slack has recently emerged — it only formally launched in February — as a new hotshot. But it’s still small. The company says it has 60,000 daily users and 15,000 paid seats.

Slack raised the funding because of strong investor interest, said Slack CEO Stewart Butterfield, who co-founded Flickr.

Slack was already nearly cash-flow positive, according to Butterfield, but the new funding will be used for hiring and possibly acquisitions of small teams.

Most of all, “it helps for certain classes of customers” that might be worried about Slack’s staying power, explained Butterfield. “This makes it a lot tougher for anyone to acquire us.”

“Walmart and Comcast-type companies are more conservative,” Butterfield noted — though both are already customers.

Slack had previously entertained acquisition interest from companies including Dropbox.

This is a very competitive space, where Microsoft bought Yammer for $1.2 billion in 2012. Butterfield noted that Andreessen Horowitz and Accel did not lead the round because they already have investments in companies that are somewhat competitive with Slack — Asana and Atlassian, respectively. The two firms landed in that situation because Slack was a pivot from a quirky online game called Glitch that never took off.

This article originally appeared on

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