Team communication app Slack is 2 years old today. And the app has picked up some seriously impressive growth in that time period: It now has 2.3 million daily active users, up from 2 million two months ago.

Slack currently has 675,000 paid seats, up from 570,000 in December, and is generating more than $64 million in annual recurring revenue, the company announced today in an infographic.

The recently launched Slack App Directory is now home to 280 apps, up from 150 in December. And Slack now sends 1.5 billion messages each month, the company said.

Slack competes with Microsoft’s Yammer, VMware’s Socialcast, Facebook at Work, Atlassian’s HipChat, and other commercially available tools. There are also open source alternatives.

San Francisco-based Slack was founded as a company in 2009 and raised a $160 million funding round at a $2.8 billion valuation last year. The company now has 369 employees.

Our coverage of the actual launch of the Slack app on February 12, 2014, is here.