How to implement idempotent APIs in ASP.NET Core

Idempotent APIs ensure applications are robust, reliable, and fault-tolerant by preventing duplicate requests caused by network issues or client-side errors. This guide explains how to implement them in ASP.NET Core, with a focus on making HTTP POST methods idempotent through custom logic. The process involves assigning unique keys to requests, checking for these keys on the server side, and ensuring requests are processed only once. Code examples are provided for creating such APIs in ASP.NET Core using Visual Studio 2022.