How This Course Works

Most system design material falls into one of two camps: dense theory with nowhere to apply it, or lab exercises that assume you already know the theory. This course is the bridge between the two. Every chapter teaches one concept, then hands you off to a real level in the HLD Lab where you actually build it.

The course is organized into six tiers, each containing a few modules, each containing a handful of chapters. Tiers get progressively harder: Foundations assumes zero prior knowledge, and by the time you reach Global Scale & Capstone you are combining a dozen concepts into systems like Uber, Netflix, and Datadog.

• -Tier 0 - Orientation: this module. How to use the course and how to think about design problems.
• -Tier 1 (Foundations): the web, servers, and the three-tier architecture every app starts from.
• -Tier 2 - Data & Performance: databases, caching, rate limiting, sharding.
• -Tier 3 (Distributed Systems Core): consistency, async messaging, real-time systems, APIs.
• -Tier 4 (Scale & Reliability): storage at scale, distributed transactions, microservices, observability.
• -Tier 5 (Global Scale & Capstone): multi-region architecture and full case studies.

Each chapter ends with a Lab Bridge: a card telling you exactly which HLD Lab level applies what you just read. The loop is: read a chapter, take the short check-yourself quiz if there is one, then go solve the linked level. Come back, read the next chapter, repeat. By the time you reach the capstones, the "building" part will feel familiar because you have already practiced every piece of it.

Some chapters embed a deep-dive from the ScaleDojo Wiki instead of re-explaining a concept from scratch, and you will see a small "Wiki" tag on those. The Wiki entries are more reference-dense; the course text around them gives you the narrative and the ordering.