3v4l.org

run code in 300+ PHP versions simultaneously
<?php echo "<form method='POST' action='" . "<?php echo \$_SERVER['PHP_SELF'];?>'>"; echo "\n"; echo "<form method='POST' action='" . '<?php echo $_SERVER[\'PHP_SELF\'];?>\'>'; echo "\n"; echo '<form method="POST" action="<?php echo $_SERVER[\'PHP_SELF\'];?>">'; echo "\n"; echo '<form method="POST" action="' . htmlentities($_SERVER['PHP_SELF']) . '">';

preferences:
52.12 ms | 402 KiB | 5 Q