This Chart Shows Why Slack Is Called One Of The Most Viral Enterprise Apps Ever

Slack, a business communication app created by Flickr cofounder Stewart Butterfield, is growing like crazy. In just six months, it's added more than 125,000 active users, and each of them is using the app for almost 10 hours a day, according to Slack.

On Wednesday, billionaire investor Marc Andreessen, who also happens to be a Slack investor, tweeted a little chart that perfectly shows the kind of growth Slack has been enjoying.

I first tweeted about Slack's viral growth on Feb 9; here's what's happened since. Unprecedented. @SlackHQ pic.twitter.com/U5xUdF8BHJ

- Marc Andreessen (@pmarca) August 13, 2014

When Andreessen first mentioned Slack back in February, it had only around 15,000 users. That means Slack has grown almost 10x in just a little over six months.

In a recent interview with Business Insider, Butterfield said the growth has been purely by word-of-mouth and a lot of it came through Twitter. He also said he intends to replace workplace email and instant messaging with Slack.