My company currently does nightly searched of our client list, and manually adds new client email addresses to Constant Contact by cut and paste.  We really want to get rid of this manual process and automate it.  I started by looking at the v2 API, but it only has limited support for custom fields, which we heavily use.   Looking at the v3 API, I am a bit confused by your examples, especially by the redirect URI etc.  Since this is a stand alone client, I have no server to redirect to.   After reading up on OAuth2, it looks like I need to use the Backend Application Flow process, but I don't see any references to this sort of process in Constant Contact.   Any clarification or examples would be greatly appreciated. ... View more