Onyx is exceptionally easy to customize. This is because all Onyx applications are built on top of Onyx data driven platform, the Onyx eBusiness Engine, and inherit the customization framework that is native to the platform. Because the application use the platform, a customer can literally drop a component into any point in any Onyx business transaction that can do something as simple as invoke a workflow, or as complex as pass data to another application.
Onyx supports customization with any language that can be used to write COM components. Examples are Visual Basic and C++.