System Design Interview Course

Lesson 1 • Communicating Designs Effectively

Covers how to narrate design decisions aloud and draw clear diagrams under time pressure. Directly improves interview performance scores.

Lesson 2 • Structured Problem-Solving Framework

Teaches a repeatable four-step method: clarify requirements, estimate scale, design components, and discuss trade-offs. Anchors every design session in a consistent process.

Lesson 3 • Core Vocabulary and Concepts

Introduces essential terminology: latency, throughput, availability, and consistency. Provides a shared language used throughout all subsequent chapters.

Lesson 4 • What System Design Interviews Test

Clarifies the evaluation criteria interviewers use and how design rounds differ from coding rounds. Sets expectations for the entire course.

Lesson 1 • Compute and Memory Sizing

Explains how to size servers, CPU cores, and RAM based on request load and processing cost. Grounds hardware decisions in quantitative reasoning.

Lesson 2 • Storage and Bandwidth Estimation

Covers estimating data volume per event, total storage over time, and network bandwidth. Connects storage needs to database and infrastructure choices.

Lesson 3 • Traffic and Request Rate Estimation

Teaches how to derive queries per second from daily active users and usage patterns. Produces the traffic baseline that drives all capacity decisions.

Lesson 1 • DNS, CDN, and Load Balancing Basics

Explains how traffic is routed from client to server through DNS resolution, CDNs, and load balancers. Connects networking to availability and latency goals.

Lesson 2 • HTTP and REST Fundamentals

Reviews HTTP methods, status codes, and REST constraints relevant to API design. Establishes the baseline protocol knowledge assumed in all API discussions.

Lesson 3 • RPC and gRPC Patterns

Introduces remote procedure call semantics and how gRPC improves on REST for internal services. Prepares candidates to discuss service-to-service communication.

Lesson 1 • Choosing the Right Storage Solution

Provides a decision framework for selecting storage based on access patterns, consistency needs, and scale. Synthesizes all storage knowledge into actionable interview guidance.

Lesson 2 • NoSQL Database Categories

Surveys key-value, document, column-family, and graph databases with their ideal use cases. Enables candidates to match data models to storage engines.

Lesson 3 • Database Sharding and Partitioning

Teaches horizontal partitioning strategies including range, hash, and directory-based sharding. Addresses hotspot prevention and cross-shard query challenges.

Lesson 4 • Relational Databases and SQL Design

Covers schema normalization, indexing strategies, and query optimisation for relational stores. Provides the SQL foundation required before exploring NoSQL alternatives.

Lesson 1 • Cache-Aside, Write-Through, and Write-Back

Compares the three primary cache population and write patterns with their consistency trade-offs. Enables correct pattern selection for any read or write workload.

Lesson 2 • Caching Fundamentals and Terminology

Defines cache hit, miss, eviction, and TTL, and explains where caches fit in a system. Establishes vocabulary used throughout the chapter.

Lesson 3 • Distributed Cache Design

Covers consistent hashing, cache cluster topology, and handling node failures in distributed caches. Scales single-node cache knowledge to production-grade systems.

Lesson 4 • Cache Invalidation and Stampede Prevention

Addresses the hardest caching problems: stale data, thundering herd, and cache poisoning. Equips candidates to discuss cache correctness in high-traffic scenarios.

Lesson 1 • Horizontal vs. Vertical Scaling

Contrasts scaling up hardware with scaling out instances, including cost and complexity trade-offs. Establishes the scaling philosophy underlying all distributed system design.

Lesson 2 • Load Balancing in Depth

Covers Layer 4 vs. Layer 7 load balancing, sticky sessions, and global server load balancing. Connects load distribution to both performance and availability goals.

Lesson 3 • Redundancy and Failover Patterns

Teaches active-active and active-passive redundancy, automatic failover, and leader election. Directly maps to designing systems that meet high availability SLAs.

Lesson 4 • Rate Limiting and Throttling

Explains token bucket, leaky bucket, and sliding window algorithms for controlling request rates. Protects system stability under traffic spikes and abusive clients.

Lesson 1 • Backpressure and Queue Management

Teaches how to detect and handle queue overflow, consumer lag, and backpressure propagation. Prevents async pipelines from becoming bottlenecks under load.

Lesson 2 • Publish-Subscribe and Event Streaming

Covers pub-sub fan-out, topic partitioning, and consumer group mechanics for high-throughput streams. Enables design of event-driven architectures at scale.

Lesson 3 • Idempotency and Exactly-Once Semantics

Explains how to design idempotent consumers and achieve exactly-once processing despite retries. Addresses correctness in distributed async systems.

Lesson 4 • Message Queues and Task Queues

Introduces producer-consumer patterns, queue semantics, and at-least-once vs. exactly-once delivery. Provides the foundation for all async processing designs.

Lesson 1 • Designing a Real-Time Chat System

Builds a chat architecture covering WebSocket connections, message storage, and presence detection. Combines real-time protocols, async queues, and storage design.

Lesson 2 • Designing a Distributed File Storage

Designs chunk-based file storage with metadata management, replication, and upload flow. Applies distributed storage and consistency concepts to a concrete system.

Lesson 3 • Designing a Social Media Feed

Covers fan-out on write vs. read, ranking, and pagination for a news feed system. Integrates async messaging, caching, and database sharding in one design.

Lesson 4 • Designing a URL Shortener

Walks through requirements, key generation, storage, and redirect flow for a URL shortening service. Demonstrates applying estimation, storage, and caching skills together.

Lesson 5 • Designing a Ride-Sharing Location Service

Covers geospatial indexing, real-time location updates, and driver-rider matching at scale. Demonstrates combining streaming, caching, and geospatial data structures.