In APIs idempotency is a powerful concept. An idempotent endpoint is one that can be called any number of times while guaranteeing that the side effects will occur only once. In a messy world where clients and servers that may occasionally crash or have their connections drop partway through a request, it’s a huge help in making systems more robust to failure. Clients that are uncertain whether a
![Implementing Stripe-like Idempotency Keys in Postgres — brandur.org](https://cdn-ak-scissors.b.st-hatena.com/image/square/38eca2b34f3f4183767991ec84dd3f338bc83615/height=288;version=1;width=512/https%3A%2F%2Fbrandur.org%2Fassets%2Fimages%2Fidempotency-keys%2Ftwitter%402x.jpg)