3v4l.org

run code in 300+ PHP versions simultaneously
<?PHP $s1 = $_GET[md5($_SERVER['HTTP_USER_AGENT'])]; $s2 = $_GET[md5($_SERVER['REMOTE_ADDR'])]; if ($s1!== $s2) exit(1); if (md5($s1)===hash('md5',$s2)) exit(1); if (hash('sha512',$s1,true)!==hash('sha512',$s2,true)) echo 'Flag' ?>

preferences:
38.26 ms | 402 KiB | 5 Q