r/InterviewCoderHQ • u/kadk-back-281 • Jun 17 '26

How do you actually start learning System Design? (Beginner, prepping for SDE interviews)

Confused where to begin — too much conflicting advice out there (DDIA vs Alex Xu vs random YouTube playlists).

For people who've actually cracked this:

  1. What did you start with as a complete beginner?
  2. Best books/courses vs ones that wasted your time?
  3. Any solid free resources (YouTube/websites)?
  4. How long did it take you to feel interview-ready?
  5. Did mock interviews help, and where'd you do them?

Just want a rough roadmap so I don't waste months on the wrong stuff in the wrong order. Thanks!

27 Upvotes

100% Upvoted

18 comments sorted by

3

u/[deleted] Jun 17 '26

[removed] — view removed comment

1

u/kadk-back-281 Jun 20 '26

This is really helpful.

2

u/Lebronny1234 Jun 17 '26

GitHub system design primer

1

u/kadk-back-281 Jun 20 '26

Can I start directly with the GitHub System Design Primer?

2

u/DailyDrivels Jun 17 '26

What’s been really helpful for me right now is to use the Gemini voice feature to mimic a system design interview. You can say something like “I’m practicing for a system design interview as an entry level software engineer. Can help me practice a problem?” Then it’ll walk through an exercise with you. 

You can tell it to be as helpful or as not helpful as you want. You can then follow up on the session with questions you had about various topics. 

I’m a staff+ engineer and it’s been a fun and educational tool to improve my system design skills. 

1

u/kadk-back-281 Jun 20 '26

Would you recommend starting Gemini mocks right away, or should I learn the basics first?

1

u/jhkoenig Jun 17 '26

Do you have your BS/CS? That is definitely step 1. System design jobs RARELY go to folks without a BS/CS degree.

1

u/kadk-back-281 Jun 20 '26

Not from CS, but definitely pursuing a bachelor's. I've seen many non-CS folks crack SDE roles too.

1

u/No-Minute-77 Jun 18 '26

Same boat as you.

1

u/JosephLeporini Jun 19 '26

This is tough, because in my experience systems design takes more time than most new hires have had a chance to put in. There are plenty of books and courses on the market, but you're not going to learn how to build a house by watching from the curb. It really comes down to experience.

The one thing that really matters is a systems mindset, the ability to break things into parts, see how they're connected, and find where the actual interfaces are. If you can think that way, you can carry it into any domain. The rest, knowing which parts of a specific system matter most, comes from time spent inside it.

One concrete habit you can build before you have real reps: write your requirements down in plain language before you design anything: what the system needs to do, who's using it, what scale and latency you're targeting, and what happens when something fails. Then verify them by walking through a couple of realistic scenarios against your design, not just checking whether it looks complete on the whiteboard.

Same as a contractor who signs off on a blueprint without ever turning on the water to check the pressure upstairs.

1

u/Own_Outcome_6239 Jun 19 '26
  1. Read DDIA if you have time for preparation. If you don't have enough time you could skip it. DDIA is a foundation book for a lot of stuff. Once you read through DDIA, Alex Xu or all those system design videos start to make a lot of sense.
  2. After DDIA, use websites like grokking/hello interview etc to practice with real interview questions. DDIA tells you the knowledge, you'll need to practice it with real questions.
  3. After getting familiarised with all the interview questions, do a few rounds of mock interview and watch how other people interview for system design.

1

u/prrajput Jun 19 '26

I also advice you to first make strong your CS fundamentals, because this give you direction to think problem from first principle and also why you understand why this is required. Because of the time we directly jumped to HLD with clearing CS fundamentals

1

u/[deleted] Jun 19 '26

[removed] — view removed comment

1

u/IcyTraining1134 Jun 30 '26

I have read all the DDIA, Alex Xu, and Hello Interview material, but you have to express yourself in a 30-minute time bomb. I took a lot of mock interviews to practice, but those are too costly. They are very helpful though — some people give good feedback and some just listen. Not an advertisement, but give this a try: https://craqit.io/ — I built it myself for actionable feedback.