Workday (WDAY) offers cloud-based payroll and human resources services to big Fortune 500 companies. And nothing screams “big” like Amazon (AMZN) or Walmart (WMT).

Amazon claims 300,000 employees now, and has said it will add another 100,000 in the U.S. over the next year and a half. By comparison, Walmart says it has approximately 1.5 million employees in the United States and 2.3 million employees worldwide, making it the world’s largest private employer.

Amazon, according to Workday’s press release, will use Workday Human Capital Management and Workday Payroll software worldwide. No financial terms of the deal—which was signed in Workday’s third quarter ending December 31, 2016—were disclosed.

A couple of things worth noting. First, Amazon chief executive Jeff Bezos was an early investor in Workday. Second, late last year, Workday said that it would use Amazon Web Services public cloud to run some of its software.

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There have been many alliances between companies like Workday, which are dubbed Software-as-a-Service providers, and public cloud infrastructure partners over the past year. Last May, for example, Salesforce.com said it will run new applications on AWS. And, while it did not publicize it, that deal calls for Salesforce to spend $400 million a year on AWS services over the next four years.

On the flip side, Amazon got a global license to run all of Salesforce’s sales-and-marketing software across its entire organization.

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In September, Adobe Systems (ADBE) and Microsoft (MSFT) inked a similar deal with Adobe, proclaiming Microsoft Azure its “preferred cloud platform” for its online marketing software and Microsoft naming Adobe’s Marketing Cloud its “preferred marketing service”—at least for Microsoft Dynamics 365 business applications.