1. A system comprising: a non-transitory memory storing a policy of a provider of applications; and one or more hardware processors in communication with the non-transitory memory and configured for: providing source interface data from the provider via a network to enable a user of a client machine to access functionality associated with applications of the provider; receiving response data over the network from an application different from the applications of the provider and unavailable from the provider based on a service call to the application from a user request through a source user interface at the client machine; accessing the policy of the provider; accessing interface definition data associated with the application; rendering target interface data based on the response data, the interface definition data associated with the application, and the policy of the provider; providing the target interface data from the provider to the client machine; receiving an application request over the network from the application based on the providing of the service call; and providing provider data from the provider to the application based on the receiving of the application request, wherein the receiving of the response data is responsive to the providing of the provider data.