System Design Interview Questions
Practice 992 real System Design interview questions for 2026 — System Design interview questions drawn from actual interviews with detailed solutions to power focused interview preparation. Coverage spans big tech patterns and company-specific flavors from Meta, Amazon, OpenAI, DoorDash, and Google, emphasizing software-engineering fundamentals: high-level architecture, APIs, data models, scaling strategies, and component-level tradeoffs you’ll need to codify on a whiteboard or virtual diagram tool. What’s distinctive in 2026: interviewers evaluate your ability to reason about capacity, latency, consistency, fault tolerance, and operational ownership while making measurable tradeoffs; expect more questions about AI/LLM inference pipelines, vector search and feature stores alongside classic problems like caching, sharding, messaging, and geo-distribution. Prepare by practicing clear HLD-to-LLD transitions, writing concise API contracts, doing back-of-envelope capacity math, and running timed mock interviews that force diagram clarity and follow-up handling. Focus on metrics, failure modes, and deployment/monitoring choices — those separate good answers from great ones.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."
"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Design a Distributed Rate Limiter
Design a distributed rate limiting system for a large API platform. The platform has many API gateways and backend services running across multiple re...
Design ad frequency capping
Design a frequency capping system for an advertising platform. The system must ensure that a user does not see the same advertisement more than a conf...
Design Multi-Dimensional Request Rate Limiting
Design a rate limiter for a backend service. Part 1: Build a standard rate limiter that can limit incoming requests by a key such as user ID, IP addre...
Design Restaurant Search and Monitoring
Design the search component for a food delivery application. Users should be able to search for restaurants and menu items by text query, for example ...
Design a Food Delivery Cart
Design the cart subsystem for a food delivery platform similar to Uber Eats. The cart should let users: - add, update, and remove items - choose item ...
Design a Distributed Crossword Solver
Design a scalable service that solves crossword-style fill-in puzzles. A request contains a rectangular grid with blocked cells, empty cells, optional...
Design an Online Coding Judge Platform
Design an online coding practice and judging platform. The platform should let users browse programming problems, write and submit code in multiple la...
Design a Hosted Notebook Platform
Design a hosted notebook platform for interactive code execution, similar to a cloud-based notebook service. The system must support 500,000 concurren...
Design a Book Price Aggregator
Design a book purchasing marketplace where your service acts as an intermediary between customers and hundreds of partner bookstores. A customer submi...
Design an Uber Eats Cart Service
Design the shopping cart service for a food delivery platform similar to Uber Eats. The service should allow customers to add, update, and remove menu...
Design a Streaming Job Scheduler
Design a task scheduling service that continuously ingests tasks and dispatches them to workers. Each task has: - id: unique task identifier - deadlin...
Design a Distributed Crossword Solver
Design a distributed solver for crossword-like word puzzles. You are given a grid containing blocked cells and empty cells, plus a dictionary of valid...
Design Ad Frequency and Order Tracking
Design two ads-platform components. Part A: Frequency capping service. Build a service used during ad decisioning to prevent a user from seeing an ad ...
Design a Slack-Like Messaging System
Design a Slack-like team messaging system focused on sending and receiving messages in real time. Your design should cover: - Core entities such as us...
Design a stock order manager
Design an order management service for stock buy and sell requests. The system does not match trades itself. Instead, it integrates with a third-party...
Design a sandboxed cloud IDE
System design: Sandboxed cloud IDE (Colab-like) Design a multi-tenant, browser-based cloud IDE/notebook that lets users run code in an isolated sandbo...
Design a resilient bootstrap API
You are given three internal services (or internal APIs): 1) User Service: GET /user-to-consumer?user_id=... → returns { consumer_id, user_profile... ...
Design Mobile Model Usage Quotas
Design the mobile and backend API flow for controlling access limits to different AI model versions in a ChatGPT-like mobile app. Requirements: - The ...
Design Nearby Restaurant Search
Design a backend system for searching nearby restaurants. Users open a mobile app and want to find restaurants near their current location. The system...
Design Human Avoidance for Warehouse Robots
Design a software module that allows an autonomous warehouse robot to avoid humans while navigating. Your answer should cover: - Which sensors you wou...