The System Design Interview Playbook: 7 Problems That Land You the Job
Preparing for System design? Here are my favorite System Design Problems from interviews which you can use to practice
System design is one of the biggest hurdles in getting a job at Amazon, Google, Netflix, or most startups. I have seen many experienced developers with years of experience on their resumes struggle in this round due to a lack of preparation and knowledge.
That’s why it's extremely important to prepare well for interviews. It's best to start by preparing for frequently asked System design problems, such as designing YouTube and WhatsApp.
By the way, if you are preparing for System design interviews and want to learn System Design in depth then you can also checkout sites like ByteByteGo, DesignGuru, Exponent, Educative, Bugfree.ai, Codemia.io, and Udemy, which have many great System design courses and if you need free system design courses you can also see the below article.
Here are my favorite System design problems you can also use to start with. I have also linked to a detailed article where you can find the solution, but I suggest you try it on your own before looking at it:
7 System Design Problems for Practice
Here are a couple of my favorite System design questions to learn essential System design concepts and principles
1. Design YouTube or any other video streaming service like Netflix, Hotstar, or SonyLiv (Solution)
We all have used YouTube, and the best thing about this question is that we all are familiar with most of the functionality, but when it comes to designing them, it’s tricky, but since we are only considering about technical aspect and not the functional, this is a good question to start with.
Think about different functions, scalability, performance, and resiliency.
If you cannot solve, see this solution for a detailed discussion.
2. Design WhatsApp or any other chat system (Solution)
Similar to the previous question, think about message distribution, recovery, and scalability.
3. Designing a URL Shortening service like TinyURL (Solution)
This is a classic system design question that tests your ability to design a read-heavy, high-throughput service with real-world constraints like vanity URLs, expiration policies, and hash collisions.
What you'll practice:
Designing scalable databases for fast redirection
Generating unique short keys with hash functions
Load balancing and caching strategies
Ensuring idempotency and rate limiting
While the system looks deceptively simple, it introduces you to foundational design tradeoffs between speed, storage, and reliability. Every backend engineer should be able to whiteboard this with confidence.
4. Designing Instagram (solution)
This problem involves building a media-rich social network — a great test of your understanding of feed generation, photo storage, user relationships, and write-heavy systems.
What you'll practice:
Designing a photo and video storage service
Generating and distributing feeds in real-time
Handling user timelines and notifications
Sharding, CDN, and caching strategies
Designing Instagram tests your ability to handle massive scalability and supports topics like eventual consistency, fan-out strategies, and denormalized writes. It’s a popular FAANG-level interview problem.
5. Design a Library Management System (Solution)
This is a classic object-oriented design (OOD) problem that's often asked at the system design round for SDE-1/SDE-2 roles. It focuses more on entity relationships, state transitions, and real-world modeling.
What you'll practice:
Modeling real-world entities like books, patrons, and transactions
Designing inventory systems and state transitions (borrow/return)
Handling overdue penalties and search functionality
Integrating with barcode systems and digital access control
Commentary:
A great warm-up problem that showcases how to map business rules into code and APIs. This is more architectural and OOD-focused, perfect for entry to mid-level roles.
6. Design a Parking Lot (Solution)
The parking lot system is a favorite for testing real-world event handling and concurrency — think multiple entry/exit points, different vehicle types, and dynamic pricing.
What you'll practice:
Designing real-time slot availability
Modeling vehicle and parking spot types
Ticketing, billing, and gate automation
Working with sensors and IoT triggers
What looks like a toy problem can quickly scale into a concurrency-heavy, real-time system. You’ll need to think through state machines, thread safety, and event-driven architecture to ace this.
These are a few questions that I always practice before an interview. Don’t think they are only 6; if you go in-depth, it can take days to solve these questions, and each one of them will teach you many essential system design concepts and challenges you face.
If you need help or an editorial solution, then let me tell you that Codemia.io has solid, editorial-backed walkthroughs and interactive tools to practice whiteboarding and architecture diagrams
All the best with your interviews, and don’t forget to share what is your favorite System design question.
If you are preparing for System design interviews and want to learn System Design in depth then you can also checkout sites like ByteByteGo, DesignGuru, Exponent, Educative, Bugfree.ai, Codemia.io, and Udemy which have many great System design courses and if you need free System design courses you can also see the below article.
If you need a method, here is a nice step-by-step guide from ByteByteGo on how to ace your next System Design interview:
