I finally understood idempotency (with real API example)

Github Repo Link: https://github.com/muteenk/server-side-practicals I kept hearing about idempotency everywhere in backend… but nothing really clicked until I actually built it. In this video, I walk through a real API implementation of idempotency - not just theory. We handle duplicate requests, retries, failure scenarios, and edge cases that most tutorials completely ignore. If you're building payment systems, APIs, or anything critical - this is not optional. # What you’ll learn: - What idempotency actually means (beyond definitions) - Why duplicate requests can break your system - How to implement idempotency using idempotency keys + DB constraints - Handling failure after success (real-world nightmare) - Basic race condition handling using DB - What’s still missing (Redis, locks, scaling) # Tech used: - FastAPI - SQLAlchemy - MySQL / SQLite (concept applies everywhere) # Who is this for: - Backend developers - Engineers preparing for interviews - Anyone building APIs that deal with money / critical operations # Reality This is not a “perfect system” - it’s a practical implementation that actually works, and a stepping stone to more advanced patterns. # Building in public I’m documenting my journey from confused to competent backend engineer. If you're on the same path, you’ll relate. 00:00 Intro 00:15 Basic Theory 02:27 Flow Diagram Explained 05:39 Idempotency Architecture Diagram 13:48 Practical 18:50 Code Implementation Walkthrough #backenddevelopment #idempotency #systemdesign #api #fastapi #softwareengineering #coding #webdevelopment #distributedsystems #programming #devlog #learninpublic #mysql #python #engineering