mySystemDesign

BEGINNER TO ADVANCED

Design a URL shortener like bit.ly. How would you handle 1 billion URLs?

How would you design Twitter's home timeline? Handle celebrities with millions of followers.

Design a distributed cache. Handle cache invalidation and eviction at scale.

Design WhatsApp. How does message delivery work when a user is offline?

Design Netflix's video streaming. Ensure low latency globally for 200 million users.

Design a rate limiter. Explain token bucket vs sliding window algorithms.

Design Uber's ride-matching system. Find nearby drivers efficiently at scale.

Explain consistent hashing. Why use it over simple modulo hashing?

How does Kafka work internally? When would you use it vs a database?

What is the CAP theorem? Give real-world examples of CP, AP, and CA systems.

How do you shard a database? Difference between range-based and hash-based sharding?

Design a notification system to send 1 million push notifications per second.

Design a payment system. How do you prevent double charges?

Design an LRU Cache. Implement with O(1) get and put operations.

Explain SOLID principles with concrete code examples. Where does DIP get violated most?

Design a Parking Lot system. Model it with classes and relationships.

Where would you use Observer vs Strategy vs State pattern? Give a single system example.

Design an elevator scheduling system. Minimise wait time for multiple elevators.

Design a vending machine. Model state transitions and handle insufficient funds.

Design a Chess game. How do you validate moves and detect checkmate?

Design Splitwise. How do you simplify debts in a group to minimise transactions?

Design Google Docs with real-time collaboration. Handle conflicting edits.

How do you handle concurrency in system design? Explain deadlock prevention.

Design BookMyShow's seat booking. Prevent two users from booking the same seat.

Design a distributed web crawler. How do you avoid re-crawling the same URL?

Design a Truecaller like caller ID and spam blocking app.

Design a Snake and Ladder Game supporting multiple players.

Design an Amazon Locker system for package delivery and pickup.

Design a vehicle rental system like Zoomcar.

Design a distributed unique ID generator (like Twitter Snowflake).

Design a cab booking application like Uber/Ola.

Design a JSON parser from scratch. Validate untrusted JSON.

Design subscription-based sports website which can display scores, game status, history for any games.

Design for online card game say like poker or any other game.

Design a geographically partitioned multi-player card game, that supports multiple players, multiple games at a time.

Design a system to fast lookup cars on the market according to the user's geo-position.

Design an airport service that will be used to allocate a free runway when the plane is about to land.

Design a Ride Sharing Application where drivers can offer rides and riders can request rides.

Design a task planner. Different types of tasks are present - bug, feature and story.

Implement a finite state machine. One start state, multiple end states, extensible.

Design a stock exchange system. Output list of executed stocks (sell_id, buy_id, quantity, price).

Code a TextPad with display, insert, delete, copy, paste, undo, redo functionality in memory.

Design a billing and auctioning system similar to EBay.

Design Q&A application as in Amazon, Walmart for each product.

Design push notification which receives event from promotions team and sends to iOS, android, email.

Design and Implement a Simple Java GC (Eden Space, Tenured Space, Perm Space).

Design LinkedIn.

Design a video upload system for a user with low network bandwidth dropping after 50%.

Design Learning Management System / Learning app.

Design Survey similar to Google Forms / SurveyMonkey.

Design a calendar Application (similar like Google Calendar).

Design Payment Gateway like Razorpay.

Design Chat Based application like whatsapp/wechat.

Design a home automation sytem to remotely control all the switches, devices in a home.

Design Meeting Scheduler. Book a meeting in any meeting room at given interval.

Design message queueing system. Mutiple suscribers listening to regex, dependencies.

Design Employee Management Platform (payroll, IT, benefits).

Design Live Auction platform for IPL / EPL.

Design Online UML Diagram Tool like lucidchart.

Design a generic coupon/promocode system (Z% off, flat discount, specific merchants).

Design a system that returns a unique id for millions of requests globally.

Design a service to view/add/remove viewers of a document (Google Docs).

Design Appointment booking for a hospital where doctors open independent slots.

Design Online Exam Portal with score calculation, rank calculation, and MOCK tests.

Design a Plagiarism checker.

Design a business rule based engine.

Create an online music recommendation system based on genre, tempo, singer.

Design a test taking website where users can register/login, give test, see past score/rank. Questions can be MCQ, yes/no, multiple correct, images. Support resuming test on drop.

Design a service for showing HeatMap of Swiggy / Zomato agents at a time.

Design Webhook Dispatcher.

Implement service to Find the recently viewed listings on the website by the user (e.g. hotels in Bangalore).

Design a Jackpot Machine.

Designing a ID card system which employees use to access any zone/premises.

Design a Bar Graph Library.

Design a notification service for swiggy which takes in a list of users and message and notifies them. Users could be delivery men, employees, end user.

Design a backend system for FlipFit. Multiple centers, slots, workout types. Manage capacities, handle bookings, display day schedules.

Design a concurrent History tracking system where we can store and track history of registered entities.

Design a scheduler, that takes in 10 scheduling requests at a time and can execute 100 jobs at a time (http requests).

Design a system which keeps track of leaders for some contest. Like referrals leader.

Design a key value store and an Index.

Design an analytics dashboard to display machines with valid/invalid certificates.

Design a service that calls any passed endpoint at a fixed interval.

Design System where User can create alerts on StockOptions. Consume streaming data.

Design a system that is incrementally scallable upto 1000 unique ID requests/sec by 1000 devices per person for 100 years.

Design a scalable weather service that pulls data from an API.

Implement an in-memory cache module/library bounded by capacity, with dynamic eviction strategies at runtime (LRU, LFU, TTL).

Design library management system. Books, items, members, reservations, fines, due dates, barcodes.

Design an API rate limiter.