Did your site just go viral on social media, had your product pitched on [insert your local variant of "Shark Tank" here], or did your festival site just launch its ticket sale? In these scenarios, no site survives its first contact with production traffic – and by then, it's too late to find out.

That's why it is useful to know in advance how your project will behave at scale under production workloads. In this talk, I will walk you through how to implement high-scale load testing with open source tools like Grafana k6: how to write test cases that mimic user behaviour realistically, what your testing infrastructure should look like to simulate 10–100k simultaneous users, and how to incorporate regular load tests into your CI/CD pipeline — illustrated throughout with real-world case studies.