ajdevhub

    🛠️ System Design Learning Hub

    A structured 24-week course covering Low-Level Design (all 23 GoF patterns), High-Level Design (14 modules), full system design case studies, and production-grade advanced topics.

    24-Week Roadmap LLD Track A — 6/6 modules done HLD Track B — 3/14 modules done
    🗺️ View Full 24-Week Roadmap →

    Phase 0 — Foundation

    Weeks 1–2 · Prerequisites ✓ Complete

    Foundation — Networking, OS, Databases & Estimation

    TCP/IP, HTTP, DNS, OS threads & I/O, ACID, database indexing, SD interview framework, back-of-envelope estimation (QPS, storage, bandwidth).

    Track A — Low-Level Design (LLD)

    Object-oriented design, all 23 GoF design patterns, concurrency, and end-to-end LLD case studies.

    A1 · Week 3 ✓ Done

    SOLID + OOP + UML

    5 SOLID principles, 4 OOP pillars, UML class & sequence diagrams.

    A2 · Week 4 ✓ Done

    Creational Patterns

    Singleton, Factory Method, Abstract Factory, Builder, Prototype.

    A3 · Week 5 ✓ Done

    Structural Patterns

    Adapter, Bridge, Composite, Decorator, Facade, Flyweight, Proxy.

    A4 · Weeks 6–7 ✓ Done

    Behavioral Patterns

    11 patterns: CoR, Command, Observer, State, Strategy, Iterator & more.

    A5 · Week 8 ✓ Done

    Concurrency in LLD

    Thread safety, locks, semaphores, Producer-Consumer, Thread Pool.

    A6 · Weeks 9–10 ✓ Done

    LLD Case Studies

    Chess, Elevator, Library, Food Ordering, Parking Lot, Hotel Booking.

    See full LLD module map →

    Track B — High-Level Design (HLD)

    Scalability, distributed systems, databases, caching, queues, reliability, and real system designs.

    B1–B3 · Weeks 11–13 ✓ Done

    Foundations of Scale

    HLD Fundamentals, Databases at Scale, Caching.

    B4 · Week 14 ✓ Done

    Message Queues & Kafka

    Async messaging patterns, Kafka architecture (partitions, offsets, consumer groups), at-least-once vs exactly-once, backpressure.

    📖 Module → 📝 Notes →
    B5 · Week 15 ✓ Done

    URL Shortener (TinyURL)

    Base62 encoding, caching, 301/302.

    📖 Module → 📝 Notes →
    B6 · Week 16 ✓ Done

    Design Twitter/X Feed

    Fan-out on write vs read, hybrid timeline.

    📖 Module → 📝 Notes →
    B7 · Week 17 ✓ Done

    Design WhatsApp

    WebSockets, Cassandra, Presence, Group Messaging.

    📖 Module → 📝 Notes →
    B8–B10 · Weeks 8–12 🔜 Soon

    Distributed Systems

    Databases at Scale, Kafka, Distributed Systems, Scalability Patterns, Reliability.

    B11–B14 · Weeks 13–16 🔜 Soon

    Advanced Systems

    Storage Systems, Special Topics, ML Systems Design, Kubernetes & Containers.

    See HLD module plan →

    Phase 2–4 — Case Studies, Advanced Topics & Mocks

    Phase Weeks Content Status
    Phase 2 17–20 Full system designs: URL Shortener, WhatsApp, YouTube, Instagram, Dropbox, Twitter… 🔜 Coming
    Phase 3 21–22 Observability, Security, Cost Optimization, mini-projects 🔜 Coming
    Phase 4 23–24 20 mock interview problems, Capstones: Uber, YouTube, BookMyShow 🔜 Coming
    🗺️ Full Roadmap ← Learning Hub