Hello RostislavK5,
Thank you for reaching out to Constant Contact API Developer Support. My team is here to assist outside software developers with questions about building into Constant Contact's API.
It looks like we've already followed up with you directly via email, but here is the information provided for visibility on the forum:
Each of our current OAuth2 authorization flows require the use of a browser to grant access to an application on an account once at which point an application can utilize refresh tokens to maintain access without requiring further authorization through a browser window.
OAuth2 Overview:
https://developer.constantcontact.com/api_guide/auth_overview.html
Please have a look and let us know if you have any other questions!
... View more
