Performance testing is crucial for evaluating the stability and responsiveness of systems under varying workloads, and k6 is an open-source framework designed to facilitate this process for developers. This tutorial guides users through setting up k6 to perform load testing on an API hosted on Heroku, demonstrating how to automate these tests within a continuous integration pipeline for consistent feedback. It covers the basics of installing k6, writing and executing tests that simulate multiple users, and interpreting results both locally and via the Grafana Cloud dashboard. The tutorial also explores advanced features such as using k6's Trend metrics to analyze API request times and integrating tests with CircleCI for automated execution. Through practical examples, users learn to identify potential bottlenecks in their systems by observing performance under stress, ultimately enabling them to prepare for future demands on their applications.