Testing REST APIs is essential for ensuring software reliability, focusing on verifying API performance and security through a structured approach involving tools, techniques, and scenarios. The process requires a solid understanding of REST API principles and the preparation of a testing environment, along with crafting detailed test cases to validate API functionality against requirements. Utilizing both manual and automated testing tools like Postman and JMeter enhances efficiency and supports continuous integration workflows. Key aspects include understanding HTTP methods, validating response codes and data, and conducting security testing to protect against vulnerabilities. Load testing assesses API performance under various conditions, while sequential and dependency testing ensure robust integration and consistency. The article emphasizes the importance of a comprehensive checklist to guide the testing process, ensuring no aspect of API functionality is overlooked. Moesif is highlighted as a tool offering API analytics and monetization capabilities, supporting organizations in managing and optimizing their API strategies.