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

Ajax Domain Checker is a WordPress plugin which allow you easily to check domain name availability from your wordpress site.

Check (whois) domain names for availability. Easy integration via shortcode or widget.

Domain Check lets you search domain names, check SSL certificates and HTTPS, set email alerts for domain and SSL expiration, and get daily coupons.

A simple plugin for WordPress that allows you to display the Domain Checker for WHMCS in a nice tidy widget.