Merge's article delves into the importance and methodology of API integration testing, emphasizing its critical role in ensuring reliable, accurate, and secure data exchange between systems. The text outlines the differences between API integration and unit testing, detailing the steps and best practices for conducting effective integration tests, such as using network request mocking libraries, evaluating error handling, focusing on boundary values, and ensuring backward compatibility. Additionally, the article provides a comprehensive example of API integration testing using Python, showcasing how to test functions that integrate currency conversion and zip code information APIs. To streamline the process of managing multiple integrations, the article highlights Merge's Unified API platform, which simplifies the integration of numerous applications, thereby reducing the labor-intensive nature of in-house testing and maintenance.