How I can populate contact activities, activities should come from other portal, so that means I will add them using my app. I tried with update contacts but it only updates properties.
'Activities' can refer to a few different things ing HubSpot. If the activities you're referring to are calls, emails, notes, meetings, etc. then you're going to want to use the engagements API. If they're things like clicks, logins, or other actions then you'll need to use the timeline API (mentioned above by Daniel) or the tracking code API, depending on the use case. The timeline API docs are linked above, and I've included the engagements API and tracking code API below:
In my app I am not going to have users, I just need to populate contacts activity based on some other portal, so I think this wont work since I can not create events. I thought there may be some way to populate contacts activity from app like I can change contacts properties.
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