A WaveMaker application can have different services like Database, REST, SOAP, and all these services have API endpoints that are automatically generated by WaveMaker when they are created. So the application can act as a resource-serving microservice and these APIs can be used by other microservices/applications.
These API endpoints are automatically used by the WaveMaker application UI when they are bound to a variable. If the application is secured with a security provider the existing architecture of the WaveMaker app UI already handles the authentication of the APIs i.e., if the UI and services are in the same application.
The WaveMaker application APIs can also be invoked from different clients. To know more about What is Client.