Slack Technologies Inc. today filed an antitrust complaint in the European Union accusing Microsoft Corp. of illegally boosting Teams, the software giant’s competing team communications service.

The move comes two months after Slack Chief Executive Officer Stewart Butterfield said the technology giant is “unhealthily preoccupied with killing us.”

Microsoft Teams is a communications service that has chat features similar to those offered by Slack, as well as a videoconferencing capability. Microsoft offers the service as part of its Microsoft 365 productivity suite, previously known as Office 365.

Slack’s antitrust complaint argues that Microsoft Teams’ inclusion in Microsoft 365 is illegal and anti-competitive. Jonathan Prince, Slack’s vice president of communications and policy, said in a statement accompanying the filing that “we’re confident that we win on the merits of our product, but we can’t ignore illegal behavior that deprives customers of access to the tools and solutions they want.” Slack General Counsel David Schellhase used sharper words, saying that Microsoft “created a weak, copycat product and tied it to their dominant Office product.”

The team chat provider broke down its antitrust argument into three components. Slack says that by bundling Microsoft Teams with its productivity suite, Microsoft is “force installing” it for millions of users, blocking its removal and hiding the true cost of the service to enterprises.

The team chat provider wants the European Commission, the EU’s executive branch, to put a stop to the practice. “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,” Prince said.

The move escalates an already tense rivalry. Before the recent interview in which Butterfield argued Microsoft of being unhealthily preoccupied with the company, Slack had suggested that its competitor copied some of its ads. On Microsoft’s end, an executive from the technology giant said last year that Slack lacks the “breadth and depth” required to reinvent collaboration. 

The European Commission is currently reviewing the antitrust filing. Officials could launch an antitrust investigation into Microsoft if they find sufficient grounds to do so.

Should a probe be opened and the European Commission ends up issuing a decision that sides with Slack’s position, it could have interesting ramifications for Microsoft 365. Certain enterprise editions of the productivity suite come with additional products besides Microsoft Teams such as the Power BI business intelligence tool. If Slack successfully makes the case that including Microsoft Teams amounts to anti-competitive behavior, then Power BI and the other products that are also included in the enterprise versions of the suite might come under scrutiny.

But it remains to be seen whether the antitrust complaint will lead to an official investigation in the first place. According to Slack, the European Commission is currently reviewing its filing.

Photo: Slack