Dominion is a WordPress plugin which allow you to swiftly check domain name availability from your WordPress site. You can search for or check any generic domains and directly integrate the search result with your WHMCS domain sales page OR you can integrate the search result with a 3rd party Domain Selling site and earn affiliate revenue from them. All required options are available in the plugin.

Demo: https://codecanyon.net/item/dominion-wp-domain-checker-with-wpbakery-page-builder/24218542