SAN FRANCISCO, June 4 -- U.S. software giant Microsoft has agreed to acquire the popular code-sharing site GitHub for 7.5 billion U.S. dollars, and the deal is expected to close by the end of 2018, Microsoft CEO Satya Nedalla said Monday.

He called GitHub the "world's leading software development platform," where more than 28 million developers are already collaborating, and it is home to more than 85 million code repositories used by people in nearly every country.

"Developers are the builders of this new era, writing the world's code. And GitHub is their home," Nedalla wrote in his official blog post Monday.

"From the largest corporations to the smallest startups, GitHub is the destination for developers to learn, share and work together to create software. It's a destination for Microsoft too," he said.

A San Francisco-based startup established in 2008, GitHub has grown sharply since it announced its first outside investment in 2012. It is a cloud-based repository for source code, offering hosting, version control management and code collaboration capabilities.

It was valued at 2 billion dollars at its most recent funding round in 2015.

Microsoft is already a major GitHub user, reportedly with more than 1,000 employees pushing code to GitHub repositories.

After the acquisition, GitHub will continue to operate independently and will remain an open platform, Nedalla said.

He noted that the "acquisition will empower developers, accelerate GitHub's growth and advance Microsoft services with new audiences."

Nedalla said Microsoft Corporate Vice President Nat Friedman, founder of Xamarin and an open source veteran, will assume the role of GitHub CEO.

GitHub's current CEO, Chris Wanstrath, will become a Microsoft technical fellow, reporting to Executive Vice President Scott Guthrie, to work on strategic software initiatives, said the Microsoft CEO.