LLD Interview Blog
Problem walkthroughs, design patterns, and strategies to crack the Low Level Design round.
Guide
SOLID Principles Explained with LLD Examples | Interview Guide
10 min read
Guide
Top 10 Design Patterns for LLD Interviews | Complete Guide
12 min read
Guide
How to Crack the LLD Interview Round | Complete Strategy Guide
11 min read
Problem Walkthroughs
Parking Lot Low Level Design — Complete LLD Interview Guide
Complete Parking Lot LLD solution — class diagram, Strategy pattern for pricing, Java code, and what interviewers look for at Amazon, Flipkart. 1500+ word guide.
Ride Sharing Low Level Design (Uber/Ola) — LLD Interview Guide
Complete Uber / ride sharing LLD solution — driver matching, fare calculation, trip state machine, class diagram and Java code. Asked at Uber, Ola, Swiggy interviews.
Movie Ticket Booking Low Level Design (BookMyShow) — LLD Guide
Design a movie ticket booking system with concurrent seat booking, seat locking, pricing strategy, and payment flow — asked at Swiggy, Razorpay, BookMyShow interviews.
Elevator System Low Level Design — Complete LLD Interview Guide
Design a multi-elevator control system with optimal assignment, SCAN algorithm, and State pattern. Detailed class breakdown for advanced LLD rounds.
URL Shortener Low Level Design (bit.ly) — LLD Interview Guide
Design a URL shortening service with Base62 encoding, custom aliases, TTL, and click analytics. Common in Google, Microsoft, and startup LLD rounds.
Chat Application Low Level Design (WhatsApp) — LLD Interview Guide
Design a WhatsApp-like messaging system — 1-on-1 chats, group chats, message status, Observer pattern for real-time delivery. Common at Slack, Meta, and Zomato.
Food Delivery System Low Level Design (Swiggy/Zomato) — LLD Guide
Design Swiggy or Zomato's core system — restaurant browse, order placement, delivery partner assignment, and real-time tracking. Frequently asked at Swiggy interviews.
Library Management System Low Level Design — LLD Interview Guide
Design a library system with book borrowing, fine calculation, and notifications. Classic beginner LLD problem asked in entry-level SDE interviews.
ATM Machine Low Level Design — Complete LLD Interview Guide
Complete ATM machine LLD solution — State pattern, Chain of Responsibility for cash dispensing, Java code, class diagram and FAQ. Asked at Paytm, PhonePe, Razorpay.
Notification System Low Level Design — LLD Interview Guide
Design a multi-channel notification service (Email, SMS, Push, In-App) with rate limiting, retry logic, and user preferences. Common at Razorpay, PhonePe.
LRU Cache Low Level Design — Complete LLD Interview Guide
Design an LRU cache with O(1) get/set using Doubly Linked List + HashMap, TTL support, and thread safety. Extremely common at FAANG interviews.
Payment Gateway Low Level Design — Complete LLD Interview Guide
Design a payment processing system with idempotency, multiple payment methods, fraud detection hooks, and webhook notifications. Core topic at Razorpay, PayU.
Rate Limiter Low Level Design — Token Bucket, Sliding Window LLD Guide
Design a rate limiter with Token Bucket, Sliding Window, and Fixed Window algorithms. Strategy pattern, distributed state, and burst handling explained.
Splitwise Low Level Design — Expense Splitter LLD Interview Guide
Design a Splitwise-like app with equal, exact, and percentage splits, balance tracking, and debt simplification algorithm. Asked at fintech SDE interviews.
Social Media Feed Low Level Design (Twitter/Instagram) — LLD Guide
Design a Twitter or Instagram feed with posts, follows, fan-out strategies, trending hashtags, and notification system. Advanced LLD for senior SDE rounds.
Job Scheduler Low Level Design — Distributed Cron LLD Interview Guide
Design a job scheduling system with cron support, priority queues, retry with backoff, and distributed workers. Senior-level LLD problem at Amazon, Flipkart.
Hotel Booking System Low Level Design (OYO) — LLD Interview Guide
Design a hotel booking platform with room availability, dynamic pricing, cancellation policy, and concurrent reservation safety. Common in product-based SDE rounds.
Inventory Management System Low Level Design — LLD Interview Guide
Design a warehouse inventory system with stock reservation, audit trail, multi-warehouse transfers, and auto reorder. Asked at Amazon, Flipkart SDE interviews.
Event Ticketing System Low Level Design (Ticketmaster) — LLD Guide
Design a high-concurrency ticket booking system with seat holds, waiting lists, dynamic pricing, and overselling prevention. Advanced LLD for senior engineers.
Logger System Low Level Design — Logging Framework LLD Guide
Design a flexible logging system with multiple handlers, formatters, and log levels. Chain of Responsibility, Singleton, and Observer patterns explained.
Top LLD Problems for Software Engineering Interviews
A curated list of the 20 best Low Level Design problems asked at Amazon, Flipkart, Swiggy, Uber, and other product companies — grouped by difficulty with Java code examples.