API testing has significantly evolved from using basic tools like cURL to more sophisticated platforms such as Postman, which not only simplifies end-to-end testing but also serves as a collaborative tool for API development. This tutorial explains how to utilize Postman’s command-line utility, Newman, to automate API tests, detailing the process from setting up a Postman environment and creating a collection for user endpoints to writing tests using Chai assertions. Moreover, it guides setting up a test automation project using CircleCI and Newman, demonstrating how to export Postman collections and environments, configure the CircleCI pipeline, and execute automated tests. The integration of CircleCI’s Newman orb enhances the testing process by automating the pipeline, generating detailed reports, and ultimately streamlining the testing workflow beyond manual efforts.