Business software maker Slack confirmed that it has raked in an additional $250 million in a Series G funding round led by SoftBank Vision Fund. That brings total funding for the eight-year-old company to a whopping $841 million and valuation to $5.1 billion.
Slack offers work-based messaging and chat software that has gained traction in companies of all sizes. It has also inspired an array of “Slack killers” from other software companies.
The Financial Times reported the funding news on Sunday.
The additional funding will bring Slack the “long term operational flexibility and resources” to enable it to move fast as the market develops, Slack CEO Stewart Butterfield said in a statement emailed to Fortune.
In the email, Deep Nishar, senior managing partner at SoftBank Vision Fund, characterized Slack as “the operating system” for businesses in which teams need to collaborate “effectively.”
As noted, Slack messaging software is popular but faces a growing number of competitive products from well-funded rivals including Microsoft (msft) with Microsoft Teams, Cisco (csco) with Spark, Google (googl) with Hangouts Chat, and Atlassian (team) with Stride.
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Last week, San Francisco-based Slack announced a new shared channel feature that will let workgroups at different companies—which must be paid Slack accounts—set up shared channels, thus enabling a marketing team at a company work in a channel with their advertising or PR agency.
It also added support for French, German, and Spanish languages to what had been an English-only product. The new funding means Slack should be able to keep adding features—and marketing them—to customers worldwide.
At that time, Butterfield said Slak has 2 million paid users across 50,000 teams, up from 1.5 million paid users in October 2016