Mine

<?php

if (getenv('REQUEST_METHOD') == 'POST') {
  $url = $_POST[url];
  $txt = $_POST[txt];
} else {
  $url = $_GET[url];
  $txt = $_GET[txt];
}
?>

<form action="<?= $PHP_SELF ?>" method="POST">
URL:<input type="text" name="url" value="<?= $url ?>"/><br>
Text:<input type="text" name="txt" value="<?= $txt ?>"/><br>
<input type="submit">
</form>
<?php
if ($url) {
$remote = fopen($url, 'r');
$html = fread($remote, 1048576);
fclose($remote);
if (preg_match("/\b".$txt."\b/i", "$html")) {
   echo "A match was found.";
} else {
   echo "A match was not found.";
}
}
?>