System Design Prep
Design systems the way senior engineers do: clear requirements, sound trade-offs, no hand-waving.
About this course
System Design Prep teaches you to lead a 45 to 60-minute architecture interview from a vague prompt to a defensible design. You start with a repeatable framework for scoping requirements and estimating scale, then build up the building blocks interviewers expect you to reason about: load balancers, caches, databases, queues, replication and consensus.
The second half of the course is 13 end-to-end case studies, from a URL shortener to a payment system. Each one includes a recorded mock interview with an experienced interviewer, annotated architecture diagrams, a deep dive into the hardest component, and a quiz on the trade-offs.
The course is written for mid-level to staff engineers, and it calls out what changes in the bar at each level, so you know how much depth to show and where to go wide instead.
What you'll learn
- Run a design interview with a clear structure: requirements, estimates, API, data model, architecture, deep dives
- Estimate QPS, storage and bandwidth quickly with back-of-the-envelope maths
- Choose between SQL and NoSQL stores and explain the trade-off for the access pattern
- Apply caching, sharding and replication strategies and describe how they fail
- Reason about consistency models, quorums and consensus without getting lost in theory
- Design event-driven systems with queues and streams, including idempotency and retries
- Walk through 13 classic interview systems end to end
- Identify bottlenecks and single points of failure, and propose concrete mitigations
- Calibrate your depth to the level you're interviewing for, from mid-level to staff
Course index
14 sections · 87 lessons · 28h total · 5 free previews
- Welcome and how to use this coursePreview10m
- How system design interviews are scored at each levelPreview18m
- The 6-step framework: from prompt to deep divePreview20m
- Clarifying questions that set up a strong design12m
- Common failure modes and how to avoid them14m
Frequently asked questions
Do I need distributed systems experience to take this course?
No. The building-block sections assume you've built a web application, but not that you've run large-scale infrastructure. Every concept is explained from the ground up before it's used in a case study.
Which levels is this course aimed at?
Mid-level (L4/E4) through staff (L6/E6). Each case study includes notes on what a strong answer looks like at each level, so you know where to go deep.
Are the mock interviews real?
They're recorded sessions with experienced interviewers and engineers playing the candidate, unscripted. They include the mistakes, recoveries and follow-up questions you'll see in real interviews.
What tools do I use to draw diagrams?
The workspace includes a diagramming canvas with the standard component shapes. Most companies use a shared whiteboard tool such as Excalidraw during interviews, and the shapes match that style.
How long does the course take?
About 6 to 8 weeks at 5 hours a week. If you're short on time, complete the framework and building-blocks sections and then the four case studies flagged as most common.
Is this useful for frontend or mobile engineers?
Yes for the fundamentals, but frontend and mobile design rounds focus on different concerns. The UI & Frontend, iOS and Android add-ons each include a client-side system design section.
Other core courses
Together they cover every round in a typical loop.
Add-ons
Role-specific prep to take alongside the core courses.
JavaScript, React, browser internals and frontend architecture interviews
17 questions · 21+ hours
ML fundamentals, ML coding and large-scale ML system design
8 questions · 15+ hours
Linux, CI/CD, infrastructure as code and cloud platform interviews
11 questions · 13+ hours
Swift, SwiftUI, UIKit and mobile architecture interviews
8 questions · 12+ hours
Kotlin, Jetpack Compose, coroutines and Android architecture interviews
5 questions · 11+ hours
Smart contracts, Solidity, the EVM and cryptographic protocols
8 questions · 11+ hours
Ready to start System Design Prep?
Designing scalable, reliable distributed systems for architecture rounds