Despite its quirky design, Slack seems to continue to grow steadily and now has more than three million daily active users—on weekdays at least—up from just under two million six months ago. It has also crossed a new milestone: more than two million simultaneously logged in users, up from just one million back in October.

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The company also touts 77 organizations from the Fortune 100 list as customers to demonstrate that it’s not just a tool for tiny startups—big companies use it too, Slack argues.

With that said, more than half of its daily active users are still freeloaders as only 930,000 are paying customers. Slack is far from alone in its industry. Everyone from Facebook (FB) to Dropbox and longtime workplace software provider Atlassian (TEAM) are vying to become the tool employers use to connect their teams.

Perhaps because of this on-going race, Slack says it has recently hired its first vice president of sales, Robert Frati. Frati was previously at Salesforce and Oracle, and he will lead Slack’s efforts to land large corporate accounts to add to its roster which already includes Comcast, Intuit, eBay, Under Armour, and EA.