The Vonage SIM Swap API is a powerful tool designed to mitigate SIM swap fraud, a malicious technique where criminals hijack phone numbers to bypass two-factor authentication and gain access to sensitive accounts. The API detects recent changes to a user's phone number, allowing it to prevent account takeovers. By authenticating with the API using a valid access token obtained through a JSON Web Token (JWT), users can check if their SIM has been swapped recently. If a swap has occurred, the API returns a boolean value indicating whether the swap was detected within a specified time frame. The tutorial demonstrates how to integrate the Vonage SIM Swap API into a web application using Node.js and Express, providing a secure login system that detects SIM swaps and prevents unauthorized access.