This handbook covers the core concepts, architecture patterns, scalability techniques, databases, caching, APIs, distributed systems, cloud architecture, security, observability, and real-world system design case studies.

You’ll find:

• 60+ HLD and System Design topics
• Architecture and data-flow diagrams
• Key concepts and terminology
• Design trade-offs and decision-making
• Scalability and reliability patterns
• Common pitfalls and edge cases
• Real-world system design examples
• Interview questions from Easy → Medium → Hard
• Practical interview and whiteboarding tips
• Curated resources for deeper learning

Whether you’re starting System Design or doing last-minute interview revision, this handbook is designed to help you learn faster and structure your answers better.

Completely free and open source.