Workplace messaging service Slack has filed a formal complaint against Microsoft Corporation with the European Commission, accusing it of anti-competitive practice.
It says Microsoft is illegally "abusing its market dominance" and removing the competition in an alleged breach of EU law.
The complaint concerns Microsoft's move to include its Teams app in an installation process for Microsoft Office users.
"Microsoft has illegally tied its Teams product into its market-dominant Office productivity suite, force installing it for millions, blocking its removal, and hiding the true cost to enterprise customers,” Slack said in a statement on Wednesday.
Jonathan Prince, vice president of communications and policy at Slack, said the company was a threat to Microsoft's business in enterprise software but offered a superior product.
“But this is much bigger than Slack versus Microsoft – this is a proxy for two very different philosophies for the future of digital ecosystems, gateways versus gatekeepers,” Prince said.
“Slack simply wants fair competition and a level playing field," added David Schellhase, general counsel at Slack.
"We’re asking the EU to be a neutral referee, examine the facts, and enforce the law.”
The European Commission is to review Slack's complaint and decide whether to open a formal investigation into Microsoft’s practices.
Under EU competition law, companies can be cited for "limiting production, markets or technical development to the prejudice of consumers".
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,” said David Schellhase.
But in a statement to Euronews, Microsoft hit back at Slack, arguing that Teams has been embraced by the market "in record numbers" due to video-conferencing during the COVID-19 pandemic.
"We’re committed to offering customers not only the best of new innovation but a wide variety of choice in how they purchase and use the product," said a Microsoft spokesperson.
"We look forward to providing additional information to the European Commission and answering any questions they may have."
Slack says Microsoft is "reverting to past behaviour ... during the ‘browser wars'."
In 2013, the European Commission fined Microsoft €561 million for failing to honour commitments and offer users a choice of web browser.
It followed a complaint in 2009 that Microsoft had tied its web browser, Internet Explorer, to its dominant client PC operating system Windows, at the expense of rivals.
The EU said this was the first time that the Commission had fined a company for non-compliance with a commitment decision.
Microsoft was said to have cooperated with the Commission at the time and provided information to assist the investigation.
In a separate EU decision in 2004, Microsoft was also found to have abused its dominant position by tying Windows Media Player to the Windows operating system, and fined €497.2 million.