System Design Interview PDF
System Design has taken the tech industry by storm. I first entered Big Tech — Microsoft, specifically — in the mid-2000s where I worked on what would become Azure. At the time, System Design wasn't a formalized discipline, and my colleagues and I were learning as we went as we grappled with the new world of distributed systems.
Since then, System Design is a formal skillset concerning building and maintaining scalable and efficient distributed systems. Some degree of System Design knowledge is expected from various tech roles, from software engineers to technical project managers. To assess this crucial skill set, the System Design Interview (SDI) had become common practice in various top tech companies (especially FAANG/MAANG).
Having conducted hundreds of System Design Interviews throughout my career, I'm eager to share the tips and tricks that will help you succeed in this interview round.
Today, I'll share what you need to know to prepare for the System Design Interview, including:
What makes System Design Interviews unique
An 8-week roadmap for System Design Interview prep
How to prep effectively if you're short on time
Let's get started.
Understanding the System Design Interview#
The System Design Interview isn’t about writing lines of code but showing how you’d build an entire system. It’s like being an architect sketching out the plans for a house.
You'll likely be given an open-ended problem in the interview, such as "Design Quora" or "Design Uber." Companies usually ask open-ended questions to evaluate how you can navigate ambiguity and seek out clarifications.
As a first step, it's a good idea to evaluate what you know based on the question you're given, then ask clarifying questions about requirements and constraints. From there, you'll be able to identify:
What the system needs to do (i.e., functional requirements)
How to make the system scale as it grows (i.e., nonfunctional requirements)
What makes System Design Interviews unique#
Unlike other technical interviews, the System Design Interview is heavily concerned with communication. Here's why: there's no right or wrong answer to a given System Design problem. There are various paths to the same goal.
This means:
Your thought process is just as important as your final solution
You must communicate your thinking throughout the interview
In fact, you should even limit your time designing in the interview to allow for 5-10 minutes of discussion and feedback at the end of your interview.
While some people are intimidated by the communication-heavy nature of System Design Interviews, it's what I like most about them. System Design Interviews are a great platform to showcase a candidate's creativity, collaboration skills, and openness to feedback — they allow you to present that you're a well-rounded engineer with both technical skills and soft skills.
How do you prepare for the System Design Interview?#
Preparing for the System Design Interview requires a strategic approach, especially when time is a factor. The key is to balance your available time with the depth of preparation using targeted resources.
Below, I'll provide an 8-week roadmap to success as well as a strategy for streamlining your prep.
8-week System Design Interview roadmap#
Note: This roadmap can be adapted for any timeframe that suits you.
Week 1: Laying the foundation#
If this is going to be your first System Design Interview, you'll need to start from scratch with a strong foundation for your interview prep.
Start with learning about:
Operating systems, networking, and low-level design (OOD)
Key design principles and patterns
Designing simple systems, such as a parking lot or a vending machine
Week 2: Grokking distributed system concepts#
Understand microservices, the CAP theorem, consistency models, partitioning, sharding, replication, consensus, atomicity, and concurrency
Learn the key principles of System Design
Weeks 3-4: Learning building blocks#
System Design fundamentals are the building blocks of any successful system, shaping how a platform scales, adapts, and performs under pressure. From smart load balancing to choosing the right database (SQL vs. NoSQL) to ensuring fault tolerance, these principles empower you to create systems that aren’t just functional but future-proof and resilient. As such, mastering them is the key to handling today’s challenges and tomorrow’s growth.
Here's what you'll want to learn:
Back-of-the-envelope estimation for various workloads
Basic building blocks such as DNS, load balancers, databases, key-value stores, and CDNs
Essential components such as caches, queuing systems, pub/sub, distributed search, rate limiters, task schedulers, sequencers, blob stores, distributed monitoring, and logging
Weeks 5-6: Practice designing real-world systems#
This is when you're ready to start tackling some common System Design Interview problems.
You'll want to:
Practice common System Design problems (based on real-world systems)
Learn design problems by category to effectively tackle similar challenges (I will discuss this more deeply later in this blog)
Some of the most commonly asked System Design Interview questions at FAANG include:
Note: Some companies ask targeted questions according to the problems they currently face with their products, for which you'll need to research and understand the company's products and design challenges.
Week 7: Revising and deep diving into design problems#
Remember: There's no right or wrong answer when it comes to System Design.
This step is essential to learning how to navigate the nuances of designing scalable systems, by building your problem-solving skills and perspective.
For this, you'll want to:
Understand trade-offs of different architectures and practice explaining your designs clearly
Revise complex scenarios and consider alternative optimal solutions
Week 8: Practice with mock interviews#
This interview is your chance to prove you can see the big picture and create a solid system ready for anything. This involves hashing out details like how you’ll store data, how different parts of the app will talk to each other, and how your system will handle many users simultaneously.
That said, all your hard work is wasted if you can't effectively communicate your thinking.
To get used to discussing your thought process and ensure your interview goes smoothly, you'll want to:
Take mock interviews to simulate real-world scenarios
Get feedback and improve iteratively
This free PDF goes deeper into this roadmap and resources to help you learn each concept. You can download it below.
Short on time? Practice problems by category #
Practicing designing real-world systems is crucial to your interview prep. That said, there are an endless pool of practice problems that you could do — and you don't have endless time.
A great way to streamline your prep is to practice problems by category, rather than trying to maximize individual problems.
The thing is: many systems share similar goals. For instance, YouTube, Netflix, or Amazon Prime Video all belong to a broader category of video streaming services, which share similar requirements, including:
Allowing users to stream and search videos
High availability and reliability
In a crunch, this means that designing YouTube prepares you to design other video streaming services like Netflix, etc.
The main categories and design problems are listed below:
By practicing problems by categories, you can master key principles that apply across a handful of problems (and save time to prep for other key rounds in the interview process).
Get more insider tips: Download your free System Design Interview PDF#
Wherever you are in your System Design journey, I want to help get you to success by showing you the tools and tips I've learned from 15+ years of System Design experience.
Deepen your understanding of the System Design Interview and get more free resources by downloading the the free System Design Interview PDF below:
In case you're having trouble with the download, please reach out to support@educative.io.
Good luck with your interview—and happy learning!
Free Resources
