API debugging can be streamlined with the use of mockups, which simulate request bodies to test an API's response to various input scenarios without sending actual requests. Mocking, particularly useful for APIs in development or undergoing updates, allows developers to validate functionality and make necessary adjustments before deployment. It also helps test an API's behavior in controlled environments, safeguarding systems from potential negative impacts of genuine requests, such as those involving sensitive data or large payloads. There are two main types of request body mockups—static and dynamic—each serving different testing needs, and tools like Postman, WireMock, and Mountebank facilitate the creation and management of these mockups. Despite their advantages, mockups have limitations, such as not fully replicating an API's behavior or covering all possible scenarios, so they should be used in conjunction with actual requests for comprehensive testing. Adhering to best practices like keeping mockups up-to-date and using realistic data ensures accurate testing, ultimately leading to reliable API performance in live environments.