Slack, the company behind the popular messaging platform of the same name, on Wednesday filed a competition complaint before the European Commission against its main rival, Microsoft.

The San Francisco-based company alleges that Microsoft abused its market dominance by bundling two of its products, making it impossible for millions of customers to use its popular "office productivity suite" – which includes Word, PowerPoint, Excel and Outlook – without also installing its "Microsoft Teams" collaboration software. Microsoft Teams is similar to Slack's widely used channel-based messaging platform.

Slack has turned to Quinn Emanuel Urquhart & Sullivan's antitrust team to advise it through the process, according to people close to the matter.