This is a PHP implementation for Facebook Messenger Bot API.
The minimum requirement is that your Web server supports PHP 5.4.
Version 1.2.2 is the last with PHP ">=5.4.0" support.
As of version 2.0, PHP 7.1.3 is required.
composer require "pimax/fb-messenger-php" "dev-master"
composer require "pimax/fb-messenger-php" "<version>"
See this repo - https://github.com/pimax/fb-messenger-php-example