Event Espresso
Triggers:
New registration (succesful or pending)
Event created
Event updated
Event Deleted
etc.
Actions:
Edit event
Delete event
Register user for an event
List registrations for event/s
List event info
Eventin integration for Suretriggers has heaps of triggers and actions, so something similar for Event Espresso.
Developer documentation:
https://github.com/eventespresso/event-espresso-core/blob/master/docs/C--REST-API/ee4-rest-api-introduction.md
https://eventespresso.com/features/rest-api/