When users click "Submit" twice, what happens next could make or break your application. Idempotency ensures repeated API calls produce consistent results, saving systems from duplicate charges, mismanaged resources, and confused customers. This talk explains idempotency’s role in building reliable APIs, with practical examples to show you how to implement it effectively in your application.

We’ll share real-world stories of what happens when idempotency goes wrong (or doesn’t exist), and go through how some of the largest companies in the world choose to implement this technique. Whether you’re a seasoned API developer or new to the concept, you’ll leave with actionable insights and techniques to make your APIs smarter and more user-friendly.