1. Go to this page and download the library: Download lg-xenos/yii2-recaptcha library. Choose the download type require.
2. Extract the ZIP file and open the index.php.
3. Add this code to the index.php.
<?php
require_once('vendor/autoload.php');
/* Start to develop here. Best regards https://php-download.com/ */
public $reCaptcha;
public function rules()
{
return [
// ...
[[], \lgxenos\yii2\recaptcha\ReCaptchaValidator::className(), 'uncheckedMessage' => 'Please confirm that you are not a bot.']
];
}