Awesome
php-whois (UNMAINTAINED)
PHP class to retrieve WHOIS information.
Example of usage
<?php
$sld = 'reg.ru';
$domain = new Phois\Whois\Whois($sld);
$whois_answer = $domain->info();
echo $whois_answer;
if ($domain->isAvailable()) {
echo "Domain is available\n";
} else {
echo "Domain is registered\n";
}