API (Application Programming Interface) is the messenger that enables two software to share data and talk to each other. Using API testing tools is how development and testing teams qualify software performance before they get to the users’ hands. The benefits of using tools guided by the principles of Agile include: Earlier testing and feedback without waiting for the whole software to be completely built. Faster test maintenance and refactoring. More bugs and issues were spotted in less time compared to UI tests. More issues spotted in under less time.