An endpoint management and proxy system is described, by which users can manage and enable exposure of application programming interfaces (“APIs”) usable to cause execution of program code on a remote or third party system. Systems and methods are disclosed which facilitate the handling of user requests to perform certain tasks on remote systems. The endpoint management system allows the application developer to define and specify a first proxy API which maps to a second API associated with the remote system. The endpoint proxy system receives requests to execute the proxy API, determines the API mapping, and sends one or more backend API requests to execute program codes by the associated remote systems. Responses from the remote systems are received by the endpoint proxy system which parses and/or transforms the results associated with the response and generates an output result for response back to the user computing systems.