Microsoft and file-storage startup Box have signed a deal to sell each other's products, the latest blurring of the lines between friends and rivals in the growing business of cloud-computing.

Box builds web-based file storage and management tools, services that compete head-to-head with Microsoft's own OneDrive and Sharepoint.

Despite that rivalry, the companies have agreed to jointly sell Box services and elements of Microsoft's Azure cloud-computing platform, they said on Tuesday.

The companies say their engineering teams are also working on building more links between their products, including adding Azure the Box Zones program. That effort lets Box customers opt to store their content in specific areas of Azure's massive global network of data centers. (Box Zones already includes Azure rivals Amazon Web Services and IBM).

Cloud-computing has made some partnerships that would have seemed bizarre in the world of out-of-the-box business software of a generation ago. Microsoft during its dominance of the personal computer heyday developed a reputation for pushing customers to use its range of products at all costs, and shunning those developed by others.

But as the company prioritizes growth in its Azure cloud-computing platform, which enables other companies to build services on Microsoft's network of data centers and rented software services, the Redmond firm has abandoned some of its scorched earth tactics. The company, analysts say, is betting that customers who plug into the cloud will demand that the products they use work well with those of other technology vendors.

Box, based in Redwood City, Calif., began as a startup founded by a pair of college students in Mercer Island. The company is among a slate of startups born in the cloud era that has thrived by building on-demand, web-based tools that replicate or improve on programs companies used to run from their own servers. Box held an initial public offering in 2015, and had sales of $425 million during the most recent 12-month period.