Best free resources to learn system design in 2026?
Interviews keep asking about scale. Where did you actually learn it — courses, books, or building things? I understand the basics (load balancers, caching, queues) but I…
System Design Questions & Answers
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System design explained — scaling, caching, databases, queues and trade-offs, plus how to handle a design interview without freezing.
Discussions
What is caching and when should I use it?
Caching gets recommended for every performance problem. What is it actually doing and what are the risks of using it wrongly?
What does a technical interview at a big tech company involve?
I have an interview loop coming up at a large company and don't know what to expect across the rounds.
Horizontal vs vertical scaling — what's the difference and which comes first?
My app is slowing down as users grow. Do I get a bigger server or more servers? How do real companies decide?
What actually happens when you type a URL into the browser and press Enter?
This is apparently the classic interview question and I realize my answer is embarrassingly vague. Can someone give the answer that would actually satisfy an interviewer?
How do I evaluate whether an AI feature is actually working?
We shipped an AI feature and everyone has opinions about whether it's good. How do you measure quality of something with no single correct answer?
Monolith vs microservices for a small team — what's the honest answer?
Two-person startup, pre-launch. Every conference talk says microservices, every burned-out founder says monolith. Who's right?
What is the difference between SQL and NoSQL databases, and when do I choose each?
Every tutorial uses a different database — Postgres, MongoDB, Firebase. How do I actually decide for a real project instead of copying whatever the tutorial used?
How does caching work and what should I cache first?
I know 'caching makes things fast' but where does one actually start on a real app — browser, CDN, Redis? What's the order?
What is the difference between SQL and NoSQL databases?
Starting a project and stuck choosing between Postgres and MongoDB. What's the real distinction and how should I pick?
What is a load balancer and when do you actually need one?
Tutorials always draw a load balancer box in architecture diagrams, but my side project runs fine on one server. At what point does this become real?
How do I stop over-engineering my code?
I spend days building abstractions and configuration for features that never materialise. How do I find the right level of simplicity?
How do I start learning system design as a fresher?
Every senior role wants system design but all the resources assume years of experience. Where does someone with zero production experience actually start?
REST vs GraphQL: which API style should I use for a new project?
Starting a new full-stack project and can't decide. GraphQL looks powerful but REST seems simpler. What do teams actually pick in production and why?
How do I structure a large project so it doesn't become a mess?
My projects start clean and become unnavigable by a few thousand lines. What are the structural habits that keep things organised as they grow?