Apache Kafka
Understand Kafka mechanics through orders, analytics, CDC, traffic spikes, streaming, integration, and recovery examples.
Open guideSystem Design Guide
Components, LLD, and trade-offs.
Understand the building blocks—and learn how to choose them.
Study system components through mechanics and visual scenarios, then practise complete low-level designs from requirements to working code.
One method, every problem
LLD Interview Framework
Follow one reasoning path from an unclear prompt to a defensible design.
10 minute lesson- 1Requirements
- 2Entities
- 3Classes
- 4Code
- 5Extensions
System components
Mechanics · simulations · trade-offsLLD problem walkthroughs
Java · diagrams · simulationsElevator System
Derive the requirements, choose the objects, write the Java design, and test it with a working simulation.
Intermediate35 min
Open walkthrough Tic-Tac-Toe
Turn interview answers into game rules, complete Java classes, and a move-by-move working simulation.
Open walkthroughParking Lot
Turn vague parking rules into spot ownership, a deterministic allocation strategy, complete Java code, and an interactive lot.
Intermediate40 min
Open walkthrough Movie Ticket Booking
Derive seat holds and booking rules, make concurrent requests safe, and prove the design with complete Java and an interactive race lab.
Open walkthroughNotification System
Design asynchronous multi-channel delivery, bounded retries, thread-safe job tracking, and graceful shutdown with complete Java and an interactive worker lab.
Open walkthroughMeeting Room Scheduler
Turn time ranges into precise interval rules, choose the smallest suitable available room, and test the design with complete Java and an interactive schedule.
Open walkthroughSplitwise
Turn shared bills into exact split rules, net pairwise debts safely, and simplify repayments with complete Java and an interactive expense lab.
Intermediate50 min
Open walkthrough Ride Sharing
Separate driver matching from road routing, trace Dijkstra step by step, and complete a ride lifecycle with Java and an interactive dispatch lab.
Open walkthrough