Clearly, the codename stuck.

Butterfield’s uncommonly candid persona and Slack’s smooth interface have made the company a media darling, as well as one of Silicon Valley’s best-known “unicorns.” Slack closed its most recent round in April, bringing its funding total to $540 million and its valuation to $3.8 billion. At the time, Slack said it had 2.7 million users of which around 800,000 were using a paid version of the service—that is, a truly searchable log of all communication and knowledge.

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