3v4l.org

run code in 300+ PHP versions simultaneously
<?php $key = "yzbqklnj"; $num = 0; $finished = false; while(!finished){ $num++; echo $num; $hash = md5($key.$num); if(strpos($hash,"00000")>0){ $finished = true; } }

preferences:
48.58 ms | 402 KiB | 5 Q