Functional requirements (FR)
- Add functional requirements here.
Non-functional requirements (NFR)
- Add non‑functional requirements here.
Engineering Library
A curated index of in-depth guides, architectural breakdowns, system design patterns, and engineering notes across all technical domains.
Algorithms and strategies
000
In-depth engineering notes, core patterns, and practical trade-offs.
Complexities
Complexities of DSA
Data structures
Data structures
Problems to solve
Complexities of DSA
Special Data structures
Special Data structures
Revision Topics
Revision Topics
Java
000
In-depth engineering notes, core patterns, and practical trade-offs.
Java collection framework outline
Java collection framework outline
Java code debugging
Java code debugging and fixing compilation errors
Java Microbenching
Java Microbenching
design patterns
must know if you want to write flexible and compact code.
Java functional programming
Java functional programming
Java Streams
Java Streams usage and sort of cookbook
Java Concurrency
Java Concurrency
System design
000
In-depth engineering notes, core patterns, and practical trade-offs.
Approach for System Design
Approach for System Design
Approach for Software Architecture
Approach for Software Architecture
Cloud Computing
In-depth engineering notes, core patterns, and practical trade-offs.
Typical Pattern to keep in mind
Typical Pattern to keep in mind
Understanding the database
In-depth engineering notes, core patterns, and practical trade-offs.
Leader election
In-depth engineering notes, core patterns, and practical trade-offs.
Principles of Object-Oriented Design
Principles of Object-Oriented Design
Performamce Tuning
Performamce Tuning
Story writing
000
In-depth engineering notes, core patterns, and practical trade-offs.
Star framework
star framework for describing the behavioural questions.
Additional topics
000
In-depth engineering notes, core patterns, and practical trade-offs.
OAuth2 flow diagrams
OAuth2 authorization and token exchange flows.
Interview questions
000
In-depth engineering notes, core patterns, and practical trade-offs.
Design Dream11 (Fantasy Sports & Real-Time Leaderboard)
Principal-level architecture drill for designing a high-concurrency fantasy sports platform with real-time match scoring, high-frequency leaderboard computation, and peak traffic burst handling.
Important Questions
Important Questions
Karat Questions
Karat Questions
Coupang Staff & Principal Engineering Interview Set
Production design drills and problem-solving references from Coupang senior interview loops, covering real-time stock watchlists, movie ticketing concurrency, and rate-limiting gateways.
High Level Design (Notification Service & Job Scheduler)
Enterprise high-level architecture drill covering multi-channel notification fanout, provider circuit breaking, and distributed job scheduling.
Design Instamart (Quick Commerce 10-Minute Delivery)
Architecture drill for designing an ultra-fast grocery delivery platform (Instamart / Blinkit / Zepto) with dark store inventory, geo-fenced order routing, real-time picker-packer orchestration, and dynamic delivery SLA tracking.
System design practice
System Design Practice Drills
Production-grade architecture drills designed for Principal and Staff Engineers (L6+). Every problem is framed with explicit Functional Requirements (FR), Non-Functional Requirements (NFR), and deep-dive discussion prompts.
Design a Global Feature Flag Platform
Principal-level prompt about safe, low-latency configuration delivery across many services and regions.
Design a Global Rate-Limiting Platform
Principal-level prompt about enforcing customer and service quotas across regions without a central request-path dependency.
Design a Durable Workflow Orchestrator
Principal-level prompt about coordinating long-running business processes across unreliable services.
Design a Multi-Tenant Event Ingestion Platform
Principal-level prompt about accepting, validating, routing, and retaining high-volume events from many producers.
Design a Shared Observability Platform
Principal-level prompt about collecting logs, metrics, and traces across teams while controlling cost and protecting sensitive data.
Design a Global Identity and Authorization Platform
Principal-level prompt about identity, authorization, and policy distribution across products and regions.
Design a Flash Sale & Inventory Reservation System
Principal-level prompt about handling extreme hot-spot inventory contention without overselling, deadlocks, or database exhaustion.
Design a Multi-Currency Payment Gateway & Ledger
Principal-level prompt about idempotent payment capture, double-entry financial ledgers, and automated reconciliation across unstable payment rails.
Design a Distributed Job Scheduler & Cron Engine
Principal-level prompt about dispatching millions of delayed and recurring jobs with high precision, worker lease fencing, and tenant fairness.
Design Instamart (Quick Commerce 10-Minute Delivery)
Principal-level prompt about dark store inventory synchronization, real-time geo-fencing, picker route optimization, and dynamic delivery SLA tracking.
Design a Proximity Search & Nearby Places Platform
Principal-level prompt about spatial indexing, boundary queries, and high-frequency vehicle coordinate ingestion at global scale.
Design a Real-Time Collaborative Document Platform
Principal-level prompt about conflict-free concurrent editing, operational transformation vs CRDTs, presence broadcasting, and snapshot compaction.
Design a Distributed Key-Value Store
Principal-level prompt about building a masterless distributed storage engine with consistent hashing, tunable quorum consistency, and anti-entropy repair.
Design a Multi-Channel Notification Platform
Principal-level prompt about dispatching high-volume transactional and marketing alerts across Push, SMS, and Email with carrier circuit breakers and preference routing.
Design a Global URL Shortener with Real-Time Analytics
Principal-level prompt about sub-15ms edge redirects, collision-free distributed ID allocation, and streaming telemetry aggregation at scale.
Design a Video Ingestion, Transcoding & Streaming Platform
Principal-level prompt about parallel chunked video transcoding, adaptive bitrate streaming (HLS/DASH), and multi-tier CDN edge caching.
Spring
000
In-depth engineering notes, core patterns, and practical trade-offs.
annotations in Spring
annotations in Spring
Dbms
Low level design
000
In-depth engineering notes, core patterns, and practical trade-offs.
Practice Questions
A directory of standalone design and implementation prompts with FR, NFR, and discussion checklists.
Splitwise
Splitwise
Design a Real-Time Scoreboard & Summary Board
Low-level and system design drill for designing an ultra-low latency real-time summary board and ranking engine for competitive programming and gaming tournaments.
Counting Impressions
Counting Impressions
rate limiter
A rate limiter, at a high-level, limits the number of events an entity (user, device, IP, etc.) canperform in a particular time window.
Design question bank
Design Question Bank
140 standalone design and implementation prompts, expanded with functional requirements, non-functional requirements, and interview discussion points. Worked solutions are intentionally omitted.
Design subscription-based sports website which can display scores, game status, history for any games
Interactive and collaborative systems interview practice prompt.
Design for online card game say like poker or any other game
Interactive and collaborative systems interview practice prompt.
Design Truecaller
Application and platform design interview practice prompt.
Design a geographically partitioned multi-player card game, that supports multiple players, multiple games at a time
Transactions and commerce interview practice prompt.
design a system to fast lookup cars on the market according to the user's geo-position
Application and platform design interview practice prompt.
Design an airport service that will be used to allocate a free runway when the plane is about to land. Data structure for the same. What if the runway is not available? Message passing between control center and the plane. Focus on low-level design and code. Can the same runway be allocated to two different planes (locking)? Database storage needed?
Scheduling and resource allocation interview practice prompt.
Design a Ride Sharing Application where drivers can offer rides (origin, destination, no of seats), riders can request rides ( origin, destination, no of seats) and there is an algo to decide which driver should be given the trip in case of a collision ( maximum overlapping one)
Scheduling and resource allocation interview practice prompt.
Design a task planner. Different types of tasks are present – bug, feature and story. And their attributes are given. Also a Sprint which is a collection of tasks
Application and platform design interview practice prompt.
Implement a finite state machine
Messaging and event delivery interview practice prompt.
Design a system like Jira. It should have the following functionalities
Application and platform design interview practice prompt.
Design a stock exchange system. There is a list of stocks given with following attributes
Transactions and commerce interview practice prompt.
code a TextPad with following functionality
Application and platform design interview practice prompt.
Design Car Rental System like Zoomcar
Scheduling and resource allocation interview practice prompt.
Design a billing and auctioning system similar to EBay
Transactions and commerce interview practice prompt.
Design Q&A application as in Amazon,Walmart has it for each product
Learning and assessment products interview practice prompt.
Design a suggestion system
Search, analytics, and intelligence interview practice prompt.
Design and Implement a Simple Java GC (Java 7+)
Data systems and storage interview practice prompt.
Design LinkedIn
Application and platform design interview practice prompt.
Design a video upload system for a user with low network bandwidth
Media transfer and delivery interview practice prompt.
Design Learning Management System
Learning and assessment products interview practice prompt.
Design Survey similar to Google Forms / SurveyMonkey
Learning and assessment products interview practice prompt.
Design Logging Framework
Search, analytics, and intelligence interview practice prompt.
Design a locker
Scheduling and resource allocation interview practice prompt.
Design a calendar Application (similar like Google Calendar)
Scheduling and resource allocation interview practice prompt.
Design Guitar Inventory System
Application and platform design interview practice prompt.
Desing Payment System
Transactions and commerce interview practice prompt.
Design a stock trading system
Transactions and commerce interview practice prompt.
Design a Json Parser from scratch
Data systems and storage interview practice prompt.
Design Chat Based application like whatsapp/wechat
Messaging and event delivery interview practice prompt.
Design a home automation sytem to remotely control all the switches, devices in a home
Application and platform design interview practice prompt.
Design Maps Navigator Client for different transportation types
Learning and assessment products interview practice prompt.
Design Meeting Scheduler
Scheduling and resource allocation interview practice prompt.
Design and Implement a logger library that applications can use to log messages
Search, analytics, and intelligence interview practice prompt.
Design a configuration management system
Search, analytics, and intelligence interview practice prompt.
Design Amazon comments filtering system
Application and platform design interview practice prompt.
Design a Vending Machine
Transactions and commerce interview practice prompt.
Design Splitwise
Application and platform design interview practice prompt.
Design Mock Interview System like pramp
Application and platform design interview practice prompt.
Design Application Tracking System (ATS) like greenhouse
Search, analytics, and intelligence interview practice prompt.
Design a Logistics System
Search, analytics, and intelligence interview practice prompt.
Design CSV parser
Application and platform design interview practice prompt.
Design message queueing system
Messaging and event delivery interview practice prompt.
Design Employee Management Platform which includes payroll,IT,employee benefits and all other employee operations in one place
Application and platform design interview practice prompt.
Design User Engagment platform
Application and platform design interview practice prompt.
Design product experience platform like pendo
Application and platform design interview practice prompt.
Design Chess Game
Interactive and collaborative systems interview practice prompt.
Design Live Auction platform for IPL / EPL
Transactions and commerce interview practice prompt.
Design Unit Testing Application
Application and platform design interview practice prompt.
Design Browser testing Application like browserstack / sauce labs
Application and platform design interview practice prompt.
Design Real time collaboration application for the teams
Interactive and collaborative systems interview practice prompt.
Design Visual workplace for remote teams
Interactive and collaborative systems interview practice prompt.
Design Online UML Diagram Tool like lucidchart
Application and platform design interview practice prompt.
Design Parking Lot
Scheduling and resource allocation interview practice prompt.
Design online audio/video file downloader
Media transfer and delivery interview practice prompt.
Design Inventory System
Application and platform design interview practice prompt.
Design Warehouse Management System
Application and platform design interview practice prompt.
Design Game Streaming platform
Media transfer and delivery interview practice prompt.
Design Real-Time Translation platform
Application and platform design interview practice prompt.
Design Community based discussion platform
Application and platform design interview practice prompt.
Design application for restaurant / malls to efficiently handle waiting queue and optimizely assign the table
Application and platform design interview practice prompt.
Design online assesment platform for exam's like gre / tofel
Learning and assessment products interview practice prompt.
Design online customer verifaction platform for digital on-boarding(KYC) of the users for bank and others client's
Identity, trust, and access interview practice prompt.
Design Secure Content Management platform
Identity, trust, and access interview practice prompt.
Design Freelancing hiring platform
Application and platform design interview practice prompt.
Design monitoring and alert system for the production as well and other enviroments
Search, analytics, and intelligence interview practice prompt.
Design digital-video KYC (know your customer) verification system
Media transfer and delivery interview practice prompt.
Design online e-fiiling online income tax returns service
Application and platform design interview practice prompt.
Design job posting system dedicated to blue and grey collar workers. (multiple langs / native lang)
Application and platform design interview practice prompt.
Design System Simiar to the Product-hunt (share and discover new products)
Application and platform design interview practice prompt.
Design service like Clipboard. (try to store the maximum clips)
Application and platform design interview practice prompt.
Design system for salary info,comparsion and other info similar to the glassdoor salary / salarry.level
Application and platform design interview practice prompt.
Design pricing / product comparision system
Application and platform design interview practice prompt.
Design Virtual Event Platform for Communities / Enterprise
Application and platform design interview practice prompt.
Design system for short video/content sharing like Tiktok
Media transfer and delivery interview practice prompt.
Design Short Story Telling (Text/Images) platform like Terribly Tiny Tales
Application and platform design interview practice prompt.
Design a user activity tracking system for user on mobile
Search, analytics, and intelligence interview practice prompt.
Design in-memory (Questions like write to add,remove the table,etc)
Application and platform design interview practice prompt.
Design a login API which is secure even if SSL certification is compromised
Identity, trust, and access interview practice prompt.
How to design an API whose response will have the response from 3 other different microservices
Application and platform design interview practice prompt.
Design system which exposes two APIs
Media transfer and delivery interview practice prompt.
Design a torrent service, end to end
Media transfer and delivery interview practice prompt.
Design system like Bigbasket (local retailer's)
Application and platform design interview practice prompt.
Design a limit order book for trading system
Transactions and commerce interview practice prompt.
Design a Cache Mechanism
Data systems and storage interview practice prompt.
Design a personal stock / investment protfolio system
Transactions and commerce interview practice prompt.
Design a electronic signature system like DocuSign / EasySign
Application and platform design interview practice prompt.
Design a generic coupon/promocode system
Transactions and commerce interview practice prompt.
Design of a quizzing app
Learning and assessment products interview practice prompt.
Design a system (initially one node/server) that could handle requests on the scale of millions. It should return a unique id for each request (The id should be unique in sense that there would be only one such id ever generated)
Application and platform design interview practice prompt.
Order-Management-System-or-System-Design
Application and platform design interview practice prompt.
Implementation of Kafka
Application and platform design interview practice prompt.
Design and Implement Rocksdb
Data systems and storage interview practice prompt.
Design and Develop the Zookeeper using Rocksdb and Google's BigTable
Data systems and storage interview practice prompt.
Developing a message queueing system
Messaging and event delivery interview practice prompt.
Design a service to view/add/remove viewers of a document (like the feature in google doc)
Application and platform design interview practice prompt.
Design an Online Auction
Transactions and commerce interview practice prompt.
Design for storing chemicals with their constituents in an efficiently retrievable format
Application and platform design interview practice prompt.
Design and Architecture - Appointment booking for a hospital where each doctor can open slots independently of any time period
Scheduling and resource allocation interview practice prompt.
Design Online Exam Portal
Learning and assessment products interview practice prompt.
Build the Google Stock Wizard
Transactions and commerce interview practice prompt.
Design the Food Ordering System like Swiggy/Zomato
Application and platform design interview practice prompt.
Design the Bill Summary Feature
Application and platform design interview practice prompt.
Design Learning app (Design system where teachers can upload the content and stuedents can view that content.)
Media transfer and delivery interview practice prompt.
Design Navigation Alerts System. (Similar like Google Map Functionality.)
Search, analytics, and intelligence interview practice prompt.
Design a system which improves the quality of the data
Application and platform design interview practice prompt.
Design a Plagiarism checker
Application and platform design interview practice prompt.
Design a distributed Cache
Data systems and storage interview practice prompt.
Design a business rule based engine
Application and platform design interview practice prompt.
Design Authentication/Authorization Service which supports(otp,OAuth, etc.)
Identity, trust, and access interview practice prompt.
Design a SMS validator system
Messaging and event delivery interview practice prompt.
Design(HLD) Zipkin - A request tracing system for distributed applications. Example - A request is flowing through multiple microservices, system should be able to trace the time spent by the request and sequence followed by it
Search, analytics, and intelligence interview practice prompt.
Design Ads system for a website
Application and platform design interview practice prompt.
Design an online code judge
Application and platform design interview practice prompt.
Design Splunk like log manager system supporting queries with filters on last min, hr, day, week etc
Search, analytics, and intelligence interview practice prompt.
Design Linkedin Suggest connections feature
Search, analytics, and intelligence interview practice prompt.
Implement a wide column store like Cassandra (bonus : support secondary indexes)
Data systems and storage interview practice prompt.
Create an online music recommendation system which suggests songs according to user taste
Search, analytics, and intelligence interview practice prompt.
Design a test taking website type service where user can register/login,
Identity, trust, and access interview practice prompt.
Design a service for showing HeatMap of Swiggy / Zomato agents at a time
Search, analytics, and intelligence interview practice prompt.
Design Webhook Dispatcher
Messaging and event delivery interview practice prompt.
Implement service to Find the recently viewed listings on the website by the user. Example a user looked for hotels in Bangalore. Design a system responsible to return the recent listings for a user
Search, analytics, and intelligence interview practice prompt.
Design a Jackpot Machine
Application and platform design interview practice prompt.
Designing a ID card system which employees use to access any zone/premises
Identity, trust, and access interview practice prompt.
Design a Bar Graph Library
Application and platform design interview practice prompt.
Gym Managment System
Scheduling and resource allocation interview practice prompt.
Design an concurrent History tracking system where we can store and track history of registered entities. We should be able to onboard service and their entities to our system and start tracking changes being made to them
Search, analytics, and intelligence interview practice prompt.
Design a system which keeps track of leaders for some contest. Like referrals leader
Search, analytics, and intelligence interview practice prompt.
Design a key value store and an Index
Data systems and storage interview practice prompt.
Design an analytics to display machines which have valid certificates,Design the system with valid dashboard with all the machines with good/bad certificates
Identity, trust, and access interview practice prompt.
Design a service that calls any passed endpoint at a fixed interval
Application and platform design interview practice prompt.
Design System where User can create alerts on StockOptions
Transactions and commerce interview practice prompt.
Design a UUID generator
Application and platform design interview practice prompt.
Design a scalable weather service that pulls data from an API
Application and platform design interview practice prompt.
You are required to implement an in-memory cache module/library which you will embed in your application to improve the application performance, by holding heavily accessed (read/written) application specific objects. To start, we would begin with following minimal requirements
Data systems and storage interview practice prompt.
Design library management system
Messaging and event delivery interview practice prompt.