VMware maintains an extensive library of APIs. To browse, search, and inspect APIs across all major VMware platforms, see the VMware API Explorer page.
There were several additions to the 6.7 release that improve virtualization efforts on Mac infrastructure. William Lam of virtuallyGhetto.com prepared an extensive list detailing each offering and its functionality. For the list, see New vSphere 6.7 APIs worth checking out.
For more information on APIs for developers and automation specialists, see Introducing Developer and Automation Interfaces for vSphere 6.7.