System design interviews are among the toughest rounds in software engineering hiring. Unlike coding tests, they measure how you think about scale, reliability, trade-offs, and distributed systems under ambiguity - and most candidates struggle not because they lack knowledge, but because they've never been taught to reason through architecture decisions.
This book walks through twenty real-world system design problems - from URL shorteners and chat systems to payment platforms, video streaming, fraud detection, and real-time analytics. Each chapter goes beyond the final diagram, explaining how experienced engineers think through requirements, estimate capacity, pick databases, design caching strategies, handle failures, and defend trade-offs. Topics include distributed caches, notification pipelines, rate limiters, search infrastructure, recommendation engines, and more.
By the end of this book, readers will be able to approach system design interviews with structure and confidence, make sound architectural decisions at work, and understand how large-scale distributed systems are designed and operated in production.
What you will learn
● Design scalable distributed systems using practical patterns.
● Understand caching, sharding, replication, and load balancing.
● Build reliable systems with queues and async processing.
Who this book is for
This book is for software engineers, backend developers, full-stack developers, engineering leads, and architects preparing for system design interviews or building scalable distributed systems. Readers should have basic programming and backend development knowledge before starting this book.
Table of Contents
1. URL Shortener
2. API Gateway
3. Distributed Rate Limiter
4. Distributed Cache
5. Feature Flags
6. Metrics and Observability
7. Notification System
8. File Storage (S3-Like)
9. Search Autocomplete
10. News Feed
11. Chat System
12. Video Streaming
13. Payments
14. Web Crawler
15. CDN and Edge Caching
16. Log Ingestion Pipeline
17. Real-Time Analytics Dashboard
18. Fraud Detection
19. Recommendation System
20. Multi-Tenant SaaS Architecture
21. Ads Serving System
Appendix A: Glossary of Terms
Appendix B: System Design Interview Tips
