Various embodiments concern mechanisms for facilitating communication between network-accessible platforms for developing, hosting, or running hybrid applications that utilize resources hosted across multiple platforms. Hybrid applications cause messages or “calls” to be passed between the platforms that must be authenticated. For example, when a call is placed by a Heroku platform to a Force.com platform, the call must be authenticated for security purposes. If Heroku has not already been authenticated when the call is submitted, an authentication process is invoked. An event listener can be used to register details regarding the initial callout task, and then register or “fire” an event when the authentication process is successfully completed. Registration of the initial callout task completely separates the authentication process from the resource being invoked. Requests can be completed without requiring further user input using at least some of the details registered by the event listener.