In today's fast-paced software development world, testing plays a crucial role in ensuring the quality and reliability of applications. For Java developers working with Spring Boot, testing REST APIs can be challenging when relying on external services that are either not available or unreliable during the development phase. This is where WireMock, a powerful HTTP mocking library, comes into play. WireMock allows developers to simulate various responses from an API, test edge cases, and ensure their application can handle different scenarios gracefully. In this article, we will dive deep into why and how you should use WireMock for testing REST APIs in your Spring Boot applications. We’ll cover practical examples, demo code, results, and explain how to integrate WireMock seamlessly into your test suite.