correction.php

<?php
// Get the text from the request
$text = $_POST['text'];

// Use the LanguageTool API to correct the text
$apiUrl = 'https://api.languagetoolplus.com/v2/check';
$apiKey = 'YOUR_API_KEY';
$data = array(
  'text' => $text,
  'language' => 'en-US'
);
$options = array(
  'http' => array(
    'header'  => "Content-type: application/x-www-form-urlencoded\r\nAuthorization: Bearer " . $apiKey,
    'method'  => 'POST',
    'content' => http_build_query($data)
  )
);
$context  = stream_context_create($options);
$result = file_get_contents($apiUrl, false, $context);
if ($result === FALSE) { /* Handle error */ }
$response = json_decode($result, true);

// Extract the corrected text from the response
$correctedText = '';
foreach ($response['matches'] as $match) {
  $correctedText .= $match['replacements'][0]['value'] . ' ';
}
$correctedText .= substr($text, strrpos($text, ' '));

// Send the corrected text back to the client
echo $correctedText;
?>