$3.8 billion Slack begins its blitz on Microsoft today

Slack, the $3.8 billion business chat startup, launched Slack Enterprise Grid on Tuesday - a long-awaited product that sees the four-year-old company go after bigger customers than ever before, as a new threat from Microsoft looms.

As Business Insider previously reported, Slack Enterprise Grid makes it easier for big business customers to move to the collaboration app, making it easier and more user-friendly to work with big teams. Slack already has big customers like IBM and Capital One.

At the same time, Slack unveiled some updated stats on its growth: It has over 500 million daily active users, with 1.5 million paid users. Slack also says it now has over 800 employees working across 7 offices worldwide. That's up considerably from November 2016, when Slack told Business Insider it had 650 employees across four offices.

"Enterprise Grid adapts to how a large business is organized and the ways in which individual parts of a big company work, providing enormous flexibility to create communication structures that mirror how teams already collaborate," Slack writes in a blog entry.

Basically, the new product's name refers to the fact that customers can now work in a "grid" of interconnected Slack teams, all connected to each other. The sales team, the marketing team, and the design team can all have their own separate versions of Slack, but share some central chatrooms with each other for company-wide announcements or cross-team collaboration.

Check it out:

Behind the scenes, Slack Enterprise Grid adds security and compliance controls to make the IT department happy, including the HIPAA and FINRA certifications needed to be used in the highly-regulated healthcare and financial sectors. It also sports new integrations with popular enterprise applications, including products from database giant SAP.

Slack has been talking about launching an enterprise product of this type since at least 2015, but has long taken the stance that it needed to take the time to really get it out. Now, it launches as the market is heating up in a big way.

Microsoft has set its crosshairs on Slack with Microsoft Teams, a similar product that's included in versions of the Office 365 cloud productivity suite for business. In a blog post sent out earlier this week, Microsoft says that even in its current, beta form, over 30,000 companies have tried out Microsoft Teams. When Microsoft first unveiled Teams, Slack CEO Stewart Butterfield took out a full-page ad in the New York Times welcoming it to the space.

Meanwhile, $6 billion software company Atlassian company bought Trello, another hot Silicon Valley collaboration app, as part of a larger play to take on Microsoft Office - while also bolstering its own HipChat, one of the chief competitors to Slack. Networking giant Cisco, too, has Spark, a similar Slack-like service.

Still, Slack has something none of those competitors have: A ton of positive buzz in Silicon Valley, sustained even after years of being on the market. Slack's customers love it, and that word of mouth is helping it continue to grow like crazy. Plus, the $540 million in venture capital it's raised over the years probably helps it compete, too.