The leader is Microsoft’s Office 365 workplace software that includes apps like Word and Excel, according to the annual study from security firm Okta. But the rankings show that many corporate workers also use Office 365 competitors, meaning that they pick and chose elements of Microsoft’s software that they like while relying on other companies for the rest.

Seventy-six percent of Okta’s customers who use Office 365 also use similar workplace software from rival companies, the survey found. Of those who use Microsoft Office 365, about 32% use Box’s app to store digital files (Microsoft’s version is OneDrive) and 28% use the Slack app to chat with co-workers (Microsoft’s competitor is Teams).

Okta’s research is based on nearly 5,600 of its customers plus a survey of 1,200 U.S. workers from other companies. Okta, which went public in 2017, specializes in technology that verifies employee identities across multiple apps and services.

Additionally, Okta’s study showed that 28% of Okta customers who use Office 365 also use Google’s G Suite collection of workplace apps that includes Gmail and Drive. This is noteworthy because companies appear to be “double bundling,” the report’s authors said, referring to firms using two different collections of workplace apps simultaneously.

Okta CEO Todd McKinnon said the report shows that “the diversity of applications are growing” inside companies, meaning they are not sticking to one vendor to supply them with all their workplace software.

It’s part of a trend in enterprise software that has led to companies specializing in workplace apps working to ensure that their software products work well with third parties. Last summer, for instance, Slack partnered with other software companies like Zendesk and Atlassian.

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Of course, Okta’s business is also partially dependent on the trend that companies will use multiple enterprise apps, considering its software helps link them together.

“If one company made all the technology we would be in trouble,” McKinnon said.

Here’s the full list of the most popular business apps:

1. Microsoft Office 365

2. Salesforce

3. Amazon AWS

4. Google G Suite

5. Box

6. Slack

7. SAP Concur

8. Jira

9. Zoom

10. Cisco Meraki

11. DocuSign

12. Zendesk

13. ServiceNow

14. Dropbox

15. ADP

Update Feb. 25 10:00 AM PT

Added ServiceNow as thirteenth most popular corporate app.