Dominion is a WordPress plugin which allow you to swiftly check domain name availability from your WordPress site.

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.

WP Domain Checker is a WordPress plugin that allows you to easily check the availability of a domain name from your WordPress site.

Age Checker is an age verification plugin for WordPress. This plugin asks users to verify their age on page load.

WHOIS Lookup is a full featured PHP script that can search for WHOIS information on any website.

The WooCommerce Pincode / Zipcode Checker module is a very necessary feature to check product availability by zip / pin / zip code.