This tutorial demonstrates how to build an ExpressJS demo app that combines Twilio Verify, a fraud verification API, with LaunchDarkly feature flags to toggle extra verification layers on during spam attacks. The app allows users to sign up and includes a signup flow where the user enters their phone number during signup and receives a verification code via SMS. A LaunchDarkly flag is added to conditionally enable SMS verification, allowing developers to adjust the signup process based on local conditions such as spam spikes.