Best resources for System Design interview prep? (Beginner → Advanced)

Hey everyone 👋 I’m currently working as an **SDE at an IT company** with about **1 year of experience**, and I’m preparing for upcoming software engineering interviews. I want to seriously level up my **System Design** skills — from fundamentals to advanced distributed systems. I understand basics like REST APIs, databases, and APIs, but I’m looking for a more structured path covering: * Scalability & load balancing * Caching strategies * Databases (SQL vs NoSQL) * Sharding & replication * Message queues & async processing * Distributed systems fundamentals * Designing real-world systems (Netflix, WhatsApp, Uber, etc.) Would love recommendations for: * Books * YouTube channels/playlists * Blogs / GitHub repos * Courses (free or paid) * Mock interview platforms What resources helped *you* the most when prepping for system design rounds?