Workplace chat app Slack has been bought by business software giant Salesforce for $27.7bn.
Rumours of the mega-deal had swirled since last week and were finally confirmed by the two firms on Tuesday.
Slack began as a gaming company in 2009 before expanding into office communications and an alternative messaging system to corporate email.
The company became a major rival to Microsoft with 12 million daily users and a market value of around $25bn.
“Stewart and his team have built one of the most beloved platforms in enterprise software history, with an incredible ecosystem around it,” said Salesforce CEO Marc Benioff.
“This is a match made in heaven. Together, Salesforce and Slack will shape the future of enterprise software and transform the way everyone works in the all-digital, work-from-anywhere world.
“I’m thrilled to welcome Slack to the Salesforce Ohana once the transaction closes.”
Slack is run by former Flickr co-creator Stewart Butterfield.
“Salesforce started the cloud revolution, and two decades later, we are still tapping into all the possibilities it offers to transform the way we work. The opportunity we see together is massive,” said Mr Butterfield.
Salesforce, which has grown into one of the world’s biggest software firms, is worth nearly $220bn and this is their largest ever purchase.