For modern business software providers, app stores have become a standard feature. Salesforce pioneered the practice of giving developers a shot at pitching directly to its customers with apps. Servicenow, NetSuite and Atlassian all followed. Workday, the maker of human resources and financial software, notably is absent from the list.

That’s because Workday generally takes a much tighter approach to letting third-party software integrate with its systems than do its industry peers. The company says this helps it stay focused on making its core systems the best they can be. But Workday’s relatively closed ecosystem has frustrated some startups—such as Sapho, a maker of customized business apps—that want to tap into its systems. Workday is the second biggest subscription software company after Salesforce, with a market capitalization of $14.8 billion.