Symfony is a powerful web development framework that, like any other application, relies on external services to provide additional functionality. Twilio and Stripe are two popular companies offering APIs (Application Programming Interfaces) that enable developers to quickly implement additional features in their applications. However, due to the nature of these APIs, they often focus more on installation than security, leaving it up to the developer to ensure the security of their application. In this tutorial, we'll explore how to verify Twilio API requests in Symfony 5 to prevent malicious actors from sending unsolicited SMS messages through your application. We'll cover the following key points: Prerequisites, Setting Up Twilio, Handling Inbound SMS Messages, Validating Inbound SMS Messages, and Listening for Symfony Kernel Events. By implementing these steps, you can ensure that any incoming requests are validated and verified to prevent security breaches in your web application.