About SystemCraft

SystemCraft is a free interview prep platform for system design (HLD), machine coding (LLD), and DSA - built by engineers, for engineers preparing at Amazon, Google, Meta, Flipkart, PhonePe, Uber, and startups.

What makes this different

Most system design content online is either:

Too shallow - “use a load balancer” without explaining why or when
Too deep - 40-page production runbooks that you’d never cover in a 45-minute interview
AI-generated slop - rehashed bullet points with no real engineering judgment

SystemCraft sits at interview depth - deep enough to impress, concise enough to finish in one sitting. Every design is written as if you’re explaining it to a senior engineer interviewer.

What you’ll find here

System Design (HLD) - 18 designs

Each design follows a consistent, interview-ready format:

Naive first cut - the simplest design and exactly why it breaks
Prior art - real engineering blog posts from companies that solved this at scale
Functional & non-functional requirements - prioritized ruthlessly (top 3 only)
High-level design - components introduced incrementally with Mermaid diagrams
Deep dives (Bad / Good / Great) - the hardest problems with progressive solutions
Core flows - sequence diagrams showing how components actually interact
Key technologies - what each tool does and why it’s chosen
What’s expected at each level - Mid / Senior / Staff+ calibration

Machine Coding (LLD) - 5 problems

Full runnable solutions with:

SOLID principles and design patterns (Strategy, Observer, State, etc.)
Class diagrams and extensibility analysis
Step-by-step thought process

DSA - 225+ problems

Quick-Fire 50 cheatsheet (the 50 most-asked problems in one page)
Blind 75 and Neetcode 150 with pattern tags
Solutions in Java, Python, and C++
Company tags (Amazon, Google, Flipkart, PhonePe)

The philosophy

Patterns over problem count. Recognizing “this is a fan-out problem” beats solving 500 random LeetCode questions.
Show progression. Start simple, add complexity only when a requirement forces it. Never dump a 15-service architecture on slide 1.
Tradeoffs over prescriptions. Every deep dive shows why the naive approach fails before presenting the fix.
Real tech, real names. Redis, Kafka, Cassandra, Temporal - not generic “DB” or “queue.” But stay at design level, not implementation detail.
Free forever. No paywall. No signup. No “unlock premium to see the deep dives.”

Numbers

18 system design problems (Beginner → Advanced)
5 machine coding problems with full code
225+ DSA problems with multi-language solutions
10,000+ engineers using this monthly
0 paywalls

Who built this

Built by engineers who went through the interview grind at Indian and international tech companies, got frustrated with the state of free system design content, and decided to build the resource that should have existed.

Shipped with obsessive attention to the details that interviewers actually care about.

Contributing

Found a mistake? Have a better approach for a deep dive? Want to suggest a new design?

Drop a comment on any page

Connect

Website: systemcraft.in
Email: systemcraft.in@gmail.com