Have a look at this topic:
One possible issue with using the User Event webhook is that it fires for more events than user creation. For example, it is sent every time a user logs into the site. You will need to filter it on Zapier by checking to see if the X-Discourse-Event
header has its value set to user_created
. The “Trigger on a specific user event” section of the topic I linked to shows how to do that. The problem I’m seeing with doing this on Zapier is that it could get quite expensive processing User Event webhooks for events that you are not interested in. A webhook that only fires when a user is created or updated could be useful.