Slack is the darling of the enterprise software world, and Microsoft reportedly considered buying it for a huge sum of money.

The tech giant was supposedly mulling a bid as large as US$8 billion before ultimately deciding against a purchase, according to a report in TechCrunch. An acquisition could have made sense for Microsoft, which has been picking up companies left and right over the past few years.

Slack is right in its wheelhouse, considering that Microsoft has purchased several other productivity-focused startups, including email app Acompli and calendar app Sunrise. Those deals formed the backbone for some of Microsoft's newer productivity applications, including its Outlook app for iOS and Android.

However, according to the report, the company remains focused on pushing its own products as Slack alternatives. While executives tried to drum up support for an acquisition, several big Microsoft names, including CEO Satya Nadella and founder Bill Gates, were unconvinced. Considering that Microsoft already owns Yammer and Skype, that's understandable.

That said, Slack is on a collision course with some of the core features in Skype. The startup just began rolling out voice calling, and has plans to add video calling to the popular chat app as well.

Microsoft, for its part, is trying to develop other capabilities for its enterprise-focused Skype for Business product that Slack seems unlikely to replicate. Case in point: a Skype Meeting Broadcast feature that lets people beam a video meeting out to up to 10,000 participants over Skype.

Microsoft and Slack both declined to comment for this report.