The war for the enterprise communication market has been going on between Slack and Microsoft's Teams for some time now, especially since the latter introduced a freemium model a couple of years ago. Microsoft's service has made strides over the past few months, and last year it reached 20 million daily active users, but Slack has said it doesn't see Microsoft's offering as a threat.
Now, Slack has apparently netted a pretty big win over Microsoft. According to a report from Business Insider (via Thurrott.com), technology giant IBM has chosen Slack as its preferred platform for internal communication between employees, adding a whopping 350,000 users to Slack's customer base. This also makes IBM Slack's biggest client, and as a result, Slack's stock rose 21% following the report.
IBM has actually been using Slack since 2014, but only now has it officially adopted the service, and it'll be moving all of its employees to the platform. With a user base that big, there's no denying that being chosen by IBM is a good sign for Slack.
Of course, it's unlikely Microsoft will sit in the shadows as Slack wins over large customers, so we'll likely continue to see the feud develop over the next few months and years. Microsoft has a lot of customers for other products and services, which might help the company sell Teams to those users.