Prep Resources

Hello Interview

My top recommendation, full stop. I suggest doing two things with it.

Go through exercises in order. If you are short on time you will not get through everything, but try to read at least one per day. Each one takes about 30 to 60 minutes. The ordering on their site is genuinely well thought out and builds on itself.

As you go, keep a Google Doc with a summary of each system design. The act of writing it down is far more effective for memory than just reading, especially if you also talk through it out loud as you write. It also gives you something lightweight to review later when you do not have time to reread a full design.

For your summaries, I recommend a template you copy-paste into a new doc tab for each design. Here is what I include in mine:

• Title
• Similar problems
• Data models
• API designs (if applicable)
• High level drawing (Excalidraw lets you export as both PNG and an Excalidraw file for later editing)
• Top 3 to 5 deep dive topics

Jordan Has No Life

Great channel with a lot of material, and genuinely entertaining. That said, I found it most useful as a second opinion on designs I had already studied elsewhere, rather than a primary resource. The material can be hard to follow at times, and the series has been redone multiple times so it is not always clear which videos to watch. All of the designs are also prewritten rather than built live, which makes it harder to mentally practice what you would actually produce in an interview setting.

Worth dipping into. Just do not start here.

Books: System Design

System Design Interview Vol. I & Vol. II (Alex Xu)

I have these on my desk. The material is solid, but the presentation is dry and difficult to absorb in a way that translates naturally into an interview. The first five chapters of Vol. I are genuinely worth reading to build your foundational understanding of how systems scale. Beyond that, Hello Interview will serve you better.

Designing Data-Intensive Applications (DDIA)

A GOAT for a reason, but not necessarily the most directly applicable resource for interview prep. If you have the time, read it. It will make you a better engineer and the concepts show up constantly in system design conversations. It is also on Audible and they actually reformatted it to work well in audio form, which is rare for a technical book. If you are short on time though, Hello Interview or anything more immediately practical should come first.

Microservice Patterns

Think of this as "how do I actually apply everything in DDIA to building real applications?" Read it not just for interviews but for your career. It is a seriously under-read book. That said, the same caveat applies: get your Hello Interview reps in first before going broad.

Practice sites

LeetCode

The standard. You know you do not want to. You know you have to.

Neetcode

Excellent explanations and well organized by category. One thing to be aware of: if you practice a full category at once (for example "graphs"), you already know what technique to apply before you have even read the problem. In a real interview you get no such hint. I solved this by opening a few random problems across categories and solving them without looking at the category label first.

HackerRank

Less common but decent. Worth knowing it exists.

How to practice

Aim for one or two problems a day. Try every problem yourself first. If you are stuck for more than 10 to 15 minutes, look at the answer and learn both the naive and the optimal approaches. If easy or medium problems are giving you trouble, the gap is usually in your knowledge of the underlying algorithm or data structure. Neetcode has a solid section covering exactly this.

Books: Coding

Cracking the Coding Interview

The book that brought coding interviews to the masses. It may feel less essential now that LeetCode and Neetcode exist and are free, but the explanations are detailed and the problem-solving methodology is solid. Honestly, it skews more useful for juniors going through their first coding loop. If you are here, you already know the ropes. Still worth knowing it exists if you want deeply explained worked solutions.

The Algorithm Design Manual (Skiena)

Worth knowing about, but you probably do not have time for a full book right now. File it away for later.

AI / LLMs

Design an AI chatbot is showing up in interviews with increasing regularity. Even a basic conceptual understanding of how LLMs work will give you a real edge when these questions come up. You do not need to go deep into the math, but knowing the architecture helps you talk fluently about things like context windows, embeddings, RAG, and where the bottlenecks are.

Neural Networks by 3Blue1Brown

Genuinely the best visual introduction to how neural networks and transformers work. 3Blue1Brown has a rare ability to make deep technical concepts intuitive without dumbing them down. Watch this playlist if you want to understand what is actually happening inside an LLM, not just the API surface. It is not interview prep in the traditional sense, but it will make you a much more confident and credible voice when AI system design comes up.