Idempotency Keys: The Simple Trick That Prevents Duplicate Payments and Ghost Or

<p>Two things quietly decide whether a small application survives being used: whether its reads<br /> are indexed, and whether its writes can be repeated safely. They are usually

<h1> Idempotency Keys: The API Pattern That Saves You From Duplicate Payments and Phantom Records </h1> <p>Your user clicks "Pay" and nothing happens. So they click again. Your

<p>You hit "Submit Order" and nothing happens. The spinner just spins. Is it processing? Did the request get lost? You click again.</p> <p>If the API on the other end does not

<p>In distributed systems, failure is not an exception—it’s the default.</p> <p>Network calls fail. Services timeout. APIs return 500s. The real question isn’t <em>“Will things

<p>In this guide, we explore system. Your transaction is pending. A timeout occurs. Now you're staring at a screen wondering if you just paid $1,000 twice or if your money

<p>Every payments API has an <code>Idempotency-Key</code> header. Far fewer have written down what it means, and the ones that haven't are usually running a <code>SELECT … WHERE

<p>A few years ago, I spent about a month cleaning up duplicate charges. Every service involved already had idempotency "handled": the client sends an Idempotency-Key header, we

<p>A file gets hashed. The hash goes off to get anchored. Sometime later, a webhook arrives saying the anchor is done. That gap between "submitted" and "confirmed" is where most