Building full-stack applications can be challenging due to the dependency between front-end and back-end teams, where the former often has to wait for the latter to finish API development. Mirage.js offers a solution by allowing front-end developers to mock back-end requests in their applications, facilitating continued work without the need for a complete back-end. This tutorial guides users on setting up Mirage.js in an existing front-end application, configuring it to mimic API requests, and utilizing it for GET, POST, and DELETE operations on to-do items. By using Mirage.js, developers can save time, as it allows for quicker response times and provides insights into data flows and API structures. The tutorial also covers writing tests with Mirage for both development and testing environments, integrating with CI/CD pipelines using CircleCI, and ensuring automated workflows and testing processes are in place for smooth project management.