For the past 2 years, I’ve been working on the backend of a digital bank. One of the important concepts that I learned was about Idempotency Keys. In this article, I will discuss: What is Idempotency? Why is idempotency important in banking? What are idempotency keys? How are idempotency keys implemented? What is idempotency? An idempotent action is one that, if performed multiple times, produces the same output as if it were done once.