Slack Turns Up Heat on Microsoft With Antitrust Complaint

Last Updated: August 27, 2020

Slack has picked a fight with Microsoft Teams and filed an antitrust complaint with the EU, accusing the Redmond giant of gaining an unfair advantage by bundling Teams with Office 365.

A year ago, Slack proclaimed Microsoft Teams is not a competitorOpens a new window . Well, now Slack has openly acknowledged that Microsoft Teams’ dominance is threatening its status quo. The workplace messaging app has filed an antitrust complaint against its long-time, well-heeled rival Microsoft with the European Commission accusing the tech giant of bundling its Microsoft Teams app with cloud-based productivity suite, Office 365.

Slack’s premise is that Microsoft, the bigger of the two giants, forces its million of users to install the app without removing it, which is an illegal and anti-competitive practice. Essentially, Slack has picked a fight with Microsoft over clubbing Teams with Office 365, that has largely contributed to the growth of Teams. The business messaging app wants the EU to force Microsoft to separate Teams from the Office 365 package. This complaint is similar to the antitrust case that Microsoft faced over bundling Internet Explorer with the Windows operating system.

David Schellhase, General Counsel at Slack, sharesOpens a new window , “Microsoft is reverting to past behavior. They created a weak, copycat product and tied it to their dominant Office product, force installing it and blocking its removal, a carbon copy of their illegal behavior during the ‘browser wars.’ Slack is asking the European Commission to take swift action to ensure Microsoft cannot continue to illegally leverage its power from one market to another by bundling or tying products.”

Learn more: No, Slack Hasn’t Left the Room. It’s Still Killing EmailOpens a new window

Slack CEO Stewart Butterfield explains in a tweet about why a complaint was filed.


Slack and Microsoft have engaged in head-to-head battle for years. The company first welcomed Microsoft as a competitor by posting an open letter in the New York Times. Furthermore, in an interview with The VergeOpens a new window , Butterfield said that “Microsoft is perhaps unhealthily preoccupied with killing us, and Teams is the vehicle to do that.”


In a statement, a Microsoft spokesperson said, “We created Teams to combine the ability to collaborate with the ability to connect via video because that’s what people want. With Covid-19, the market has embraced Teams in record numbers while Slack suffered from its absence of video-conferencing. We’re committed to offering customers not only the best of new innovation but a wide variety of choices in how they purchase and use the product. We look forward to providing additional information to the European Commission and answering any questions they may have.”

This isn’t the first U.S tech giant that is under the radar of the EU. In the past, the EU has charged Google for anti-competitive behavior, while last month, the EU started antitrust investigations against Apple. The European Commission will now review the complaint before deciding whether to launch formal proceedings against Microsoft.


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Priya Jha
Priya Jha works as an Assitant Editor for Toolbox. She focuses on the latest trends and innovations in the B2B industry. With an education background in engineering, she skillfully employs her knowledge in developing stories on cloud, data, security, and emerging technologies. You can reach her at [email protected].
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