Methods, apparatus and articles of manufacture for custom interface specification in a cloud management system are disclosed. An example cloud management system includes: a first interface to communicate with a second interface external to the cloud management system; and a host to manage requests from the second interface and allocate resources to the second interface as a reverse proxy for the second interface with respect to a backend. The example host is to at least: add, at the request of the second interface, an endpoint with respect to the second interface; fetch, at the request of the second interface, data for the endpoint from the backend, the backend identified for the endpoint based on metadata in a component registry; and provide the data from the backend to the second interface.