Authentication for your integration starts with creating an app in a HubSpot Developer account. You'll use the Client ID and Client Secret from that app to initiate the OAuth handshake between HubSpot and your integration.
OAuth 2.0 allows a user to authorize your app to work with specific tools in their HubSpot account, designated by the authorization scopes you set. You can find more details about the available scopes and the tools they provide access to here.
There are 4 main steps to connecting your integration to a customers HubSpot account using OAuth:
codeappended to the URL. Use that code and your Client Secret to get an access_token and refresh_token.