Microsoft Corp. plans to nearly double its work force in India over the next four years, investing $1.7 billion and adding 3,000 jobs in a vote of confidence in one of the world’s fastest-growing markets.

The investment would be among the largest an information technology company has made in the country of 1 billion people, a country that Microsoft long has viewed as having huge potential in human capital and sales.

Much of the money would go toward creating a Windows operating system designed specifically for India and available in nine Indian languages. That could help Microsoft fend off challenges from cheaper open-source operating systems led by Linux, which has made deep inroads in India.