Instagram Low-Level Design #LLD | Feed Generation System + Code + UML | System Design Interview Prep

🎯 Instagram System Design Interview Question – Solved! Code link: https://github.com/codewithmrunmai/instagram_lld UML Link: https://lucid.app/lucidchart/b1022460-530d-4691-bfa8-4b875049e448/edit?invitationId=inv_65d9fe7e-b44d-461e-be8f-fb6e6e38bc1c In this detailed Low-Level Design (LLD) breakdown, we reverse-engineer Instagram from scratch—covering real-world use cases, class diagrams, and actual code snippets! Chapters 00:00 - Intro 00:40 - High-Level Design (Rough Flow) 04:00 - Instagram Architecture Overview 08:28 - User & Feed Microservice (Initial Thinking) 09:08 - Fan-out Discussion 10:25 - Push Model 12:39 - Kafka for Action Events 13:47 - API Request Flow 15:28 - Pull Model 16:21 - Hybrid Push-Pull Model 18:13 - Redis Sorted Set for Feed 20:30 - MongoDB as Backup Store 21:00 - Project Folder Structure 21:35 - UML Diagram 23:12 - User Microservice 26:08 - Media Service 29:18 - Post Service 30:35 - Feed Service 🔍 What’s inside this video? ✅ Feed Generation System – Push vs Pull ✅ Redis Caching + MongoDB for backup ✅ Sorted Sets for fast feed pagination ✅ TTL for expiring content like Stories ✅ UML Class Diagram & Design Patterns ✅ How scalable systems like Instagram are built ✅ Code walk-through and clean architecture Whether you're a backend beginner or prepping for FAANG-level LLD/System Design interviews, this video gives you a realistic and practical understanding of how large-scale social media apps are designed.