Bunu da kullanabilirsiniz;

<?php
ob_start("minifier");
function minifier($code) {
    $search = array(
        // Remove whitespaces after tags
        '/>[^S ]+/s',
        
        // Remove whitespaces before tags
        '/[^S ]+</s',
        
        // Remove multiple whitespace sequences
        '/(s)+/s',
        
        // Removes comments
        '/<!--(.|s)*?-->/'
    );
    $replace = array('>', '<', '\1');
    $code = preg_replace($search, $replace, $code);
    return $code;
}
?>
<!DOCTYPE html>
<html>
<head>
<!-- title of page -->
<title>Demo for minifier</title>
</head>

<body>
<!-- body of page -->
<h1>Hello World</h1>
</body>
</html>

<?php
ob_end_flush();
?>