Use the Oxxa API in PHP.
composer require ben221199/oxxa-api
$username = 'myUsername'; // Your API username
$password = 'myPassword'; // Your API password
$useMD5 = true; // When true, password is sent in its MD5 form.
$isTesting = false; // When true, payment wil not occur
$oxxaApi = new \Ben221199\Oxxa\API\OxxaAPI('https://api.oxxa.com',$username,$password,$useMD5,$isTesting);
$xml = $oxxaApi->DOMAIN_CHECK([
'sld' => 'myDomain',
'tld' => 'com',
]);