This is a PHP 8.0 and higher library that fully supports the latest Constant Contact endpoints, as it is automatically generated from the swagger.yaml file. Changes to the swagger.yaml file are track nightly with any new updates automatically published.
You will need to turn on PHP session support for the library to authenticate. Also make sure you update the composer version constraint as documented in the readme to make sure you get the latest releases as this library uses a date based versioning scheme.
You can find the library here https://packagist.org/packages/phpfui/constantcontact
Any problems, please open an issue on github.
Thank you for reaching out to Constant Contact API Developer Support.
As you may know, the request for official V3 application code samples is still under review, as we're currently still adding endpoints and capabilities to the V3 API, and Constant Contact does not plan to publish any official SDKs or sample apps until that process is complete.
In the meantime though, we appreciate you updating and sharing this valuable resource that you have compiled and opted to make available to other developers!