What is this site?
This is a personal learning guide for mastering System Design — both High Level Design (HLD) and Low Level Design (LLD) — built for software engineers preparing for interviews. Every page here represents something I’ve learned, summarized in a way that’s easy to follow and revisit.How to use this guide
Start with Foundations
If you’re new to system design, begin with the Foundations section. It covers the core mental models you’ll need before anything else.
Move to HLD
Learn the building blocks of large-scale systems — databases, caches, load balancers, and how they fit together.
Then tackle LLD
Dive into object-oriented design, SOLID principles, and design patterns with real case studies.
What’s covered
Foundations
Core concepts and how to approach any system design problem.
High Level Design
Scalability, databases, caches, queues, CDNs and more.
Low Level Design
OOP, SOLID principles, and Gang of Four design patterns.
Interview Prep
How to structure answers, avoid common mistakes, and practice.