This package requires the use of Composer to install.
$ composer require dragonmantank/activecampaign
$accountUrl = 'https://<company>.api-us1.com';
$accountKey = 'abcd';
$client = new Dragonmantank\ActiveCampaign\Client($accountUrl, $accountKey);
// Example to get contacts
$response = $client->get('contacts');