Free System Design Interview Guide on GitHub: Patterns, Questions, and Deep Dives

Preparing for the system design interview feels overwhelming because the surface area seems infinite. There are endless systems to study, and it is easy to fall into the trap of memorizing solutions to specific questions, only to freeze the moment the interviewer changes one detail.

The fix is to study patterns, not answers. Once you understand a small set of reusable building blocks, like caching, sharding, replication, and messaging, almost any design problem starts to feel familiar. That is the idea behind our new, free, open-source guide on GitHub: Grokking System Design.

Key takeaways

What is inside the guide

The free system design repo is organized so you can move from fundamentals to practice without getting lost:

• Patterns: the building blocks of system design, each as a short, practical cheat sheet. Caching, load balancing, sharding and partitioning, replication, consistency models, the CAP theorem, consistent hashing, message queues, rate limiting, CDNs, database indexing, and bloom filters.
• Questions: more than 40 classic design walkthroughs at the approach-and-trade-offs level, from Design TinyURL and Design Instagram to Design Uber, Design Google Docs, and Design a payment system.
• Deep dives: case studies of landmark distributed systems, including Dynamo, Cassandra, BigTable, Kafka, Chubby, GFS, and HDFS, the "how does X work" questions that show up in senior interviews.
• Cheat sheets and roadmaps: a repeatable interview framework, a back-of-the-envelope estimation reference, and a focused two-week study plan.

Why a pattern-based approach works

"Grok" means to understand something so completely that it becomes intuitive. Instead of memorizing a fixed list of answers, you learn the patterns that appear again and again across very different systems. Caching strategies, sharding approaches, and consistency models show up whether you are designing a URL shortener or a video platform. Once the patterns are second nature, you can assemble a strong answer to a question you have never seen before, which is exactly what interviewers are testing.

Pro Tip: Before you study any specific system, learn the interview framework first. Having a repeatable structure (requirements, estimation, API, data model, high-level design, deep dive, trade-offs) keeps you calm and organized no matter what the interviewer asks.

How to use it

A simple study path works well:

1. Read the interview framework and the estimation cheat sheet so you have a structure and the key numbers.
2. Work through the core patterns until each one feels intuitive.
3. Practice with the question walkthroughs, applying the patterns out loud.
4. Follow the two-week roadmap if you have an interview coming up soon.

For a deeper, structured path with interactive diagrams, video lessons, and full worked solutions, pair the repo with Grokking the System Design Interview, the original course the guide is based on.

Who it is for

The guide suits anyone preparing for a system design round, from engineers seeing these questions for the first time to senior candidates brushing up on distributed systems before a FAANG loop. If you are newer to the topic, start with our 25 Fundamental System Design Concepts and the System Design Cheat Sheet, then use the repo to practice.

Pro Tip: Reading about a system is not the same as being able to design it under pressure. After you study a question in the repo, close it and try to redraw the design from memory, talking through your decisions as if an interviewer were listening.

My honest take

I have watched engineers spend months memorizing specific system designs and still struggle in the real interview, because the question was framed slightly differently than they had practiced. The ones who do well are the ones who internalized the building blocks and could reason from first principles. That is why we built this guide around patterns first. It is free because the fundamentals should be accessible to everyone, and the goal is simple: help you walk into your interview able to reason, not just recall.

If the guide helps you, a star on the GitHub repo helps more engineers find it.

— Arslan

FAQ

Is the system design guide really free?

Yes. The entire guide lives on GitHub and is free to read, use, and share. It is open-source, so you can also contribute improvements.

Is the repo a replacement for the course?

No. The repo is a free companion that gives you the map: pattern summaries, practice questions, and deep dives. The full course gives you the territory, with interactive diagrams, video lessons, and complete worked solutions.

How should I start?

Read the interview framework and the estimation cheat sheet first, then study the core patterns, then practice with the questions. If your interview is close, follow the two-week roadmap.

Does it cover senior-level topics?

Yes. Alongside the classic questions, it includes deep dives into real distributed systems like Dynamo, Kafka, and GFS, which are common in senior and staff interviews.

Recommended

• Grokking the System Design Interview
• 25 Fundamental System Design Concepts
• The Ultimate System Design Cheat Sheet
• Mock Interviews with ex-FAANG engineers