The Amazon SNS Message Validator for PHP library allows you to validate that incoming HTTP(S) POST messages are valid Amazon SNS notifications. This library is standalone and does not depend on the AWS SDK for PHP or Guzzle; however, it does require PHP 5.4+ and that the OpenSSL PHP extension is installed. Next, you must create an instance of MessageValidator, and then use either the isValid() or validate(), methods to validate the message. The message validator checks the SigningCertURL, SignatureVersion, and Signature to make sure they are valid and consistent with the message data. Amazon Simple Notification Service (Amazon SNS) is a fast, fully-managed, push messaging service. Amazon SNS can deliver messages to email, mobile devices (i.e., SMS; iOS, Android and FireOS push notifications), Amazon SQS queues, and of course HTTP/HTTPS endpoints.