I recently set up PHP contact form on a website (for a friend/freelance client) that used the CtCt v2 API to handle a newsletter-opt-in checkbox in the form. All was working fine, until this client migrated his site to a new host running PHP 7.1.25 (was previous 5.x, I suppose). There was some issue with the guzzle dependency in the provided CtCt PHP SDK, and I found a post in this form where a developer pretty clearly stated that on PHP 7+, you really should be using the new v3 API.   Now that I've spend some looking at the v3 docs, though, I'm confused about Oauth. Both the client and server flows explained in the docs seem to assume a CC customer manually end user providing authentication as part of the process — but this is a very basic integration where the code living on the CC customer's own web server needs to access that owner's list data and create a contact in response to someone else's submission of a form—the site owner is not present in the transaction to authenticate themselves. Is this a case the v3 API can handle? Most likely scenario is I'm just looking at this wrong and need some explanation, I realize... ... View more