Hi @tsmorin - can you share a bit about your use case? We do support use of external APIs in our rules engine ( https://support.gainsight.com/SFDC_Edition/Rules_Engine/Admin_Guides/Call_External_API_Action_Type ) which can be used to call external systems and then have those systems take some action. For example you can create a rule to post messages to Slack using their external API ( https://support.gainsight.com/SFDC_Edition/Rules_Engine/Examples_and_Tutorials/Post_Messages_to_Slack_with_Call_External_API_Action_Type ).

Depending on your use case and the APIs available with Eloqua, you should be able to trigger actions in that system using Gainsight rules. 

@tsmorin did you get a chance to see comments posted by @dan_ahrens . 

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