Master HLD & LLD for
System Design Interviews
208 topics from high-level architecture to low-level design — taught by an AI mentor that thinks like a senior FAANG engineer. Ask follow-ups, get personalized depth, practice real interview scenarios.
No credit card required · AI mentor included · Ready in seconds
What's included
23 structured tracks covering every domain you need to ace system design rounds.
Design Twitter, YouTube, Uber, WhatsApp — full architecture walkthroughs
OOP, design patterns, class diagrams, and real LLD interview breakdowns
SQL vs NoSQL, indexing, sharding, replication, and query optimization
TCP/IP, HTTP/2, gRPC, WebSockets, DNS, and CDN internals
REST, GraphQL, gRPC, event streaming, and API gateway patterns
Kafka, Spark, data pipelines, batch vs stream processing
ML system design, feature stores, model serving, and vector databases
How Netflix, Airbnb, Stripe, and Discord solved real engineering problems
OAuth2, JWT, zero trust, rate limiting, and encryption patterns
Payment systems, ledgers, idempotency, and financial data modeling
Kubernetes, CI/CD, infrastructure as code, and multi-cloud patterns
Process management, memory, file systems, and concurrency internals
HLD & LLD topics you'll master
A sample from the full 208-topic curriculum. The 12 foundation topics are free — no sign-up required.
Free foundation topics
And 196 more (Pro/Power)
How CrackLab DesignHub works
Pick a track or topic
Browse 23 structured tracks or jump straight to any HLD / LLD topic you need for an upcoming interview.
AI explains like a senior engineer
Get deep, structured lessons with architecture diagrams, trade-off analysis, and interview-ready talking points.
Practice & get interview-ready
Work through real interview scenarios, quiz yourself, and chat with your AI mentor until you can explain it cold.
Ready to crack system design? 🏗️
Join engineers preparing for Google, Meta, Amazon, and top startups. Your AI mentor is ready — no setup, no credit card required.
Start Learning with AI →Frequently asked questions
What topics does CrackLab DesignHub cover?
208 topics across 23 structured tracks: High Level Design (HLD), Low Level Design (LLD), databases, networking, APIs, distributed systems, DevOps, security, data engineering, AI/ML systems, payments, company case studies (Netflix, Airbnb, Stripe), and more — everything a senior engineer needs for system design rounds.
Is CrackLab DesignHub free?
Yes — the free plan gives you access to a daily quota of AI-powered lessons and AI mentor chats, with no credit card required to start. 12 foundation topics are permanently free with no quota. A Pro plan unlocks unlimited access to all 208 topics.
What's the difference between HLD and LLD?
HLD (High Level Design) covers system architecture at scale — distributed systems, load balancing, caching, databases, microservices, and how large components interact. LLD (Low Level Design) covers class-level design — OOP principles, design patterns (GoF), UML class diagrams, and hands-on code problems like Parking Lot, Elevator System, and Chess. Most FAANG interviews test both.
Do I need prior system design experience?
No. The curriculum spans Foundation to Expert levels. Whether you're preparing for your first system design round or brushing up for a staff-level interview, there's a structured path for you. Topics are tagged by difficulty so you can start exactly where you need to.
Does this prepare me for FAANG / top-tier interviews?
Absolutely. The curriculum covers all common FAANG HLD topics (URL shorteners, distributed caches, notification systems, design Twitter / YouTube / Uber) and LLD topics (parking lot, elevator system, chess game) with real interview scenarios, sample talking points, and AI-powered follow-up practice.
How is this different from reading a system design book?
Books are static — you read, then guess if you understood. CrackLab DesignHub is interactive: you get animated architecture diagrams, an AI mentor you can ask any follow-up question, interview scenario practice, and real-time feedback. You don't just read about load balancing — you see it animated, ask the AI why consistent hashing is preferred, and practice explaining it out loud.
Can I get a certificate after completing the course?
Yes — CrackLab DesignHub awards a certificate of completion once you finish the curriculum. You can share it on LinkedIn or include it in your portfolio.
How long does it take to complete the full curriculum?
Most engineers finish the core HLD curriculum in 4–6 weeks studying 30–60 minutes per day. The full 208-topic curriculum (HLD + LLD + deep dives) typically takes 8–12 weeks at a comfortable pace. You can also target specific tracks for upcoming interviews — many engineers cover a focused track in a single week.