If you want to validate twitter username using PHP then you can achieve this using CURL.

Following function will check whether twitter username exists or not.

<?php
function validate_twitter_username($username)
{
$twitter_url='http://api.twitter.com/1/users/show/'.$username.'.xml';
$init = curl_init();
curl_setopt ($init, CURLOPT_URL, $twitter_url);
curl_setopt ($init, CURLOPT_CONNECTTIMEOUT, 20);
curl_setopt($init, CURLOPT_NOBODY, 1);
curl_setopt($init, CURLOPT_HEADER, 1);
curl_setopt($init, CURLOPT_RETURNTRANSFER, true);
curl_exec($init);
$result_header = curl_getinfo($init, CURLINFO_HTTP_CODE);
curl_close($init);
if( $result_header == "404" )
{
// IF username not exists return false
return false;
}else{
// IF username exists return true
return true;
}
}
if(validate_twitter_username('snilesh'))
{
echo 'Username Exists.. Please Try Other username';
}
else
{
echo 'Username Available';
}
?>