Plesk Onyx
From WHMCS Documentation
Plesk Onyx is the next release of the Plesk Web Hosting Control Panel following Plesk 12.5.
First released as a preview towards the end of 2016, Plesk Onyx is the first release of Plesk following the introduction of their new product naming convention and dropping of version numbers.
However, fundamentally Plesk Onyx is still Plesk, and is compatible with WHMCS using the Plesk module.
For information on how to configure and use Plesk with WHMCS, please refer to the Plesk documentation.