10 System Design Concepts You Must Master Before Your Next SDE Interview (with Resources)
Don’t Go Into Your System Design Interview Without Mastering This
Hello guys, System Design interviews can be intimidating, even for experienced developers, especially if you are not prepared and aiming for Big Tech companies.
Big Tech companies like Amazon, Google, Apple and Netflix test not just your coding skills but your ability to design scalable, reliable, and maintainable systems.
If you are preparing for System Design interviews and looking for tips, guidance’s and resources then you have come to the right place.
In the past, I have shared the best System Design interview books, courses, cheat sheets, and websites and in this article, I am sharing a cheat sheet of important topics for system design interviews.
When I first started preparing, I underestimated their difficulty — and faced rejections from five companies straight. Looking back, the biggest reason for my failures was weak fundamental knowledge. 🥲
If you don’t want to repeat my mistakes, make sure you’ve nailed these critical System Design concepts before your next interview.
By the way, if you are preparing for System design interviews and want to learn System Design in-depth then you can also check sites like ByteByteGo, Design Guru, Exponent, Educative, Codemia.io, and Udemy which has many great System design courses.
Those have dedicated courses and study material which you need to crack FAANG level System Design interviews. In particular Codemia.io have biggest collection of System Design problems for tech interviews from big tech companies
10 Must Know System Design Concepts for Your Next SDE Interview
Here are the 10 essential System Design concepts you must know before you go for any System design interview, both SDE and Staff level. These not just covers fundamentals but also advanced concepts like distributed transactions.
1. Fundamentals (Core Concepts)
A strong understanding of web fundamentals is non-negotiable:
- How the web works (DNS, TCP/IP, TLS, HTTP/HTTPS)
- Client-Server architecture
- REST vs gRPC
- Synchronous vs Asynchronous communication
- Stateless vs Stateful services
Tip:
Always be ready to explain how a browser fetches a webpage — it’s a favorite interviewer question.
2. Building Blocks
You must understand the core components of large-scale systems:
- Load Balancers (types, algorithms)
- Proxies (Forward Proxy, Reverse Proxy, CDNs)
- API Gateway (rate limiting, authentication, routing)
- Web Servers (Nginx, Apache basics)
Pro Tip:
Know how a Load Balancer handles millions of requests and how API Gateways manage microservices.
3. Databases
Databases are the backbone of system design:
- SQL vs NoSQL (and when to choose each)
- Indexing & Query Optimization
- Normalization vs Denormalization
- Replication, Sharding, Partitioning
- CAP Theorem & PACELC Model
- Transactions and Isolation Levels
- Data modeling for scalable systems
Practical Question:
“Design Instagram’s database schema” — these fundamentals help you answer confidently.
4. Caching
Caching can massively improve system performance:
- Why caching matters (latency and load reduction)
- Tools like Redis and Memcached
- Cache strategies (LRU, LFU, TTL, write-through, write-behind)
- Cache invalidation techniques (hardest part!)
Example Interview Tip:
Explain how Twitter caches user timelines efficiently.
5. Messaging and Queuing Systems
Modern distributed systems rely heavily on messaging:
- Message Queues: Kafka, RabbitMQ, AWS SQS
- Event-driven architecture patterns
- Publish/Subscribe model
Sample Interview Challenge:
“How would you design an event notification system like Uber Eats?”
6. System Communication
You must know how microservices talk to each other reliably:
- Service Discovery
- API Rate Limiting
- Circuit Breaker and Retry Logic
- Idempotency handling
Remember:
Failing to manage retries or rate limits often causes real-world system outages. You can also read this article to handle payment retries gracefully
7. Scalability and Performance
Hiring managers love candidates who think about scale and performance bottlenecks:
- Horizontal vs Vertical Scaling
- CDNs and Edge Caching
- Database bottlenecks and how to use Read Replicas
- Data consistency vs availability (CAP Theorem in action)
Discussion Tip:
Talk about scaling Netflix’s architecture if asked for real-world examples.
8. Security Basics
Security is critical in all designs:
- Authentication & Authorization (OAuth2, JWT, API Keys)
- HTTPS, TLS for secure data transmission
- Data encryption (in transit and at rest)
- DDOS protection, throttling, rate limiting
Example:
You should be able to design a secure login system using OAuth2.
9. High Availability and Fault Tolerance
Building resilient systems wins interviews:
- Replication across data centers
- Failover strategies and Leader Election (Raft Algorithm)
- Health checks, Monitoring, and Alerting setup
Critical Scenario:
How would you design Netflix’s system to survive a server crash?
10. Practice Systems (Must Know)
Practice end-to-end designs of these real-world systems:
- URL Shortener (TinyURL, Bitly)
- Rate Limiter Service
- File Storage System (Google Drive)
- Notification System (email, SMS, push)
- Messaging Apps (WhatsApp, Instagram)
- Social Media Platform (Facebook, Twitter)
- Ride Booking System (Uber, Lyft)
- Streaming Apps (YouTube, Spotify)
Bonus:
Sketch architectures for at least 5 of these systems before your next interview!
Best Resources for System Design Interview Preparation
Here are the resources I personally used during my preparation:
- Alex Xu’s “System Design Interview” Book (Both Volume 1 & 2)
- Interview Kick Start for Mock Interviews
- DesignGuru’s Grokking System Design Course
- Codemia.io : — Leetcode for System Design
- Concept and Coding YouTube Channel
- Hello Interview YouTube Channel and Website
- Awesome High-Level Design GitHub Repo
- Gaurav Sen’s System Design YouTube Channel
If you combine these resources with focused practice on the topics listed above, your chances of clearing the next SDE System Design round skyrocket.
And, here is a nice System Design cheat sheet from ByteByteGo to remember key System Design concepts easily
Final Words
System Design is not something you can “wing” in the interview. It requires deliberate practice, deep understanding, and strategic thinking.
Start small, build core understanding, practice scalable system designs, and you’ll stand out from 90% of candidates.
Good luck with your next interview — and don’t give up if you fail a few times. Every attempt is a step closer!
Other System Design Tutorials and Resources you may like
- Is DesignGuru’s System Design Course worth it
- Is Exponent’s System Design Course worth it?
- 10 Best Places to Learn System Design in 2025
- How to Prepare for System Design Interview in 2025
- Is ByteByteGo worth the hype?
- System Design Interview cheat sheet for 2025
- My Favorite Software Design Courses for 2025
- 3 Places to Practice System Design Mock interviews
- Is Designing Data-intensive application book worth reading?
All the best for your System Design Interviews, if you have any doubts or questions, feel free to ask in the comments.
P. S. — If you just want to do one thing at this moment, go join ByteByteGo and start learning System Design concepts, you will thank me later. Make it a goal for the new year and you will surely be a better Software Engineer.
