Use a third-party CSS or JS Framework, a self-hosted service like a CRM, or a third-party service with the site.
dotMailer API is a very simple, lightweight module that connects a Drupal website with the dotdigital API https://developer.dotdigital.com/reference/about-our-rest-api.
Important Note
This module requires the following library: Dotmailer-php (https://packagist.org/packages/drupalcoders/dotmailer-php).
Needs PHP =^7.2 in order to work
PHP =^7.2
This module contains a sub-module dotmailer_newsletter (This generates a custom 'dotMailer Newsletter Signup' block).
Ciptex RACE Web Chat is a module that allows Drupal developers to integrate Twilio Auto Pilot into their sites
Simply share your API credentials.
Note: This project is not being actively maintained due to the maintainer being in school.
This module has been moved into Acquia Connector starting with 4.0.0-beta4. Further work as a separate module has been discontinued.
A simple module integrating SendGrid's API library with Drupal.