Global DNS allows you to instantly check the DNS records across multiple servers. It provides an insight to end users on which server website is pointing to.
Demo: https://codecanyon.net/item/global-dns-multiple-server-dns-propagation-checker-php/27125682
Dominion is a WordPress plugin which allow you to swiftly check domain name availability from your WordPress site.
Demo: https://codecanyon.net/item/dominion-wp-domain-checker-with-wpbakery-page-builder/24218542
WP Domain Checker is a WordPress plugin that allows you to easily check the availability of a domain name from your WordPress site.
Demo: https://codecanyon.net/item/wp-domain-checker/9959666
Age Checker is an age verification plugin for WordPress. This plugin asks users to verify their age on page load.
Demo: https://codecanyon.net/item/age-checker-for-wordpress/20626595
WHOIS Lookup is a full featured PHP script that can search for WHOIS information on any website.
Demo: https://codecanyon.net/item/whois-lookup-ultimate-whois-information-checker-script/28782038
The WooCommerce Pincode / Zipcode Checker module is a very necessary feature to check product availability by zip / pin / zip code.
Demo: https://codecanyon.net/item/woocommerce-pincode-zipcode-checker/25036697