I’m working on a custom action [link removed, since “the community feels it is an advertisement”] that copies assets and projects to cloud object storage (inspired by this sample).
It would be nice if the custom action could send a notification to the user when the copy is complete, but I can’t find any way in the API to do this. Is there a way?
Unfortunately there is not at this time, totally hear you that this would be great to have!
I’ll link this thread to the ticket and make sure to update you if we add that capability.
Great - thanks! 
[Now a bit of text so that Discourse will let me post this reply 
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yes, it is possible to send a notification via an API.
One common method is to use to push notification service such as firebase cloud messaging or Apple push notiication service. These service allow you to send notification to mobile devices or web browser via their respective platform such notification system.