Do I have to create a HubSpot app to pull data into my private app?

[Mulan]

I have a couple of users/organizations that use both HubSpot and my private app. To give them the ability to seamlesssly transfer some of their data to their account on my app, am I required to build a HubSpot app and have them "connect" their HubSpot account to my HubSpot app (e.g. connected apps), or can my app simply use authentication processes to pull the data over without the user having to do anything in their HubSpot account? I think I'm looking for an open API approach. 

thanks for any insights!

[WendyGoh · Accepted solution]

Hey @Mulan,

You're spot on. If you'd like to manipulate with any data on a particular portal via your app, the portal would need to grant access to your app through the OAuth process. 

Hence, there isn't an Open API approach in which you can access another portal's data without the portal users' permission. 

[Mulan]

Thank you, Wendy!