Microsoft Teams has surpassed 20 million daily active users, an increase of 7 million since July, the company has revealed.

The collaboration suite, available as part of Microsoft’s premium Office 365 brand or as a free version, exceeded the popular Slack platform as being the most used business chat app earlier this year.

In fact, Teams now only sits behind Microsoft’s other chat platform Skype for Business in terms of popularity. However, the company has made it clear in the past that Teams will eventually supersede Skype as its primary tool.

Although Slack has grown to 12 million daily users as of October, that modest growth has been dwarfed by the successes of Microsoft Teams. Slack shares fell as much as 10% following Microsoft’s announcement on Tuesday, and have fallen 18% since the company’s public launch in June.

Meanwhile, Workplace by Facebook reported in October that it had surpassed 3 million subscribers, up one million since February.

Microsoft announced a batch of updates for Teams at its annual Ignite conference earlier this month, including a simple sign-on mechanism for front line workers, new integrations with Yammer and Skype, an expansion of the Advanced Threat Protection suite to cover messages within Teams, and the general availability of private chats.

Microsoft’s Office 365 subscription gives premium access to the Teams app, alongside its traditional productivity software. Commercial Cloud, the division that Teams falls under, is one of the highest performing areas of the company, making up over one-third of its overall revenue, according to third-quarter figures.

Slack hasn’t spent the year idle, having overhauled the underlying technology of its desktop app in July to help reduce RAM usage by 50% and improving loading times by 33%. The company also added new features in August that help admins manage permissions, and a Workflow Builder in October, that allows users to automate routine functions using custom workflows.