Slack has reached over four million daily active users worldwide.
The cloud-based messaging app, popular among workplaces, is considered the fastest growing business application ever with more than 1.25 million customers paying to use the service.
A number of high profile companies, such as LinkedIn, eBay, Conde Nast, and EA, use the messaging service that now has a current annual revenue of $100 million.
The service allows users to communicate with others through dedicated channels, and customise usability through apps such as Trello, Skype and Dropbox. These and other Slack plug-ins are now downloaded 415,000 times each month, hitting a total of six million downloads since the service launched in 2013.
Nearly half of all Slack users are outside the US, with customers in the UK, Japan, Germany, France and Australia.
"Continued momentum on the Slack platform is an important sign of the expanding role we play in the business software ecosystem," the company stated in a blog post.
"When we say 'Slack is where work happens', we don't just mean people sending messages to one another, but the integrated workflows, business processes, data streams and applications that spin the gears of work for tens of thousands of our business customers around the world," the firm adds.
The San Francisco-based company now employs 650 staff in seven offices globally, with offices in cities such as New York, London and Melbourne.
Slack has a number of rivals for its crown, however, with Facebook the latest to launch a competitor, Workplace, just last week.
