System Design Interview Questions
Practice 981 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 an A/B Testing Platform
Design an internal A/B testing platform for a large consumer product. The platform should let product managers and engineers create experiments, defin...
Validate virtual credit card transactions from encoded IDs
You are designing logic for a virtual credit card product. Part 1: Product reasoning Explain key benefits and drawbacks of virtual credit cards for: -...
Design personalized restaurant search and recommendations
Scenario You are designing a DoorDash-like personalized restaurant recommendation system. A user types a free-text query (e.g., “spicy ramen under $20...
Design API for split-stay combinations
Question Design an HTTP API endpoint that, given a requested date range and a collection of Airbnb listings with their availability, returns all valid...
Design User Re-engagement Notifications
Design a re-engagement system for an AI assistant product. The system should support at least two use cases: 1. Send relevant notifications to inactiv...
Design an alert notification system
Design a multi-tenant alert notification system for operational incidents. Monitoring sources send events when checks fire or recover. Users can confi...
Design a user activity query system
Problem Design a query system that allows internal consumers (e.g., customer support, risk/fraud, data analysts) to retrieve a given user's search act...
Design a crypto trading web frontend
Design the front-end architecture for a retail cryptocurrency trading web app (like a spot exchange). Assume the product needs these core screens and ...
Scale a Distributed Randomized Multiset
After designing the randomized multiset on a single machine, explain how you would scale it across multiple servers. The distributed system should sup...
Design cart and pricing engine classes
Design the core classes and interfaces for a cart & pricing engine for a food delivery marketplace (e.g., Uber Eats). This is an object-oriented / low...
Design leader election using Redis leases
Design Leader Election Using Redis Leases You have N stateless service instances all running the same code. At any instant, exactly one instance must ...
Design an Online Coding Contest Platform
Design an online coding challenge platform that supports both regular practice problems and live contests. Functional requirements: - Users can browse...
Design access control and heartbeat systems
Design two backend systems. Part A: Door access control system Design a service that manages which people can open which doors. The system must suppor...
Design a group chat system
System Design: Group Chat Design a scalable group chat system (like a basic Slack/WhatsApp group chat). Core features - Users can create groups, join/...
Determine identical files ignoring metadata
Question How would you determine whether two files contain identical bytes while ignoring all filesystem metadata? Propose and justify a hashing-based...
Design a Library Management System (API and Schema)
Design the API and database schema for a library management system. The library lends physical books to registered members. Members can search the cat...
Design a Twitter-like service
Design a simplified Twitter-like system that supports: - Users can post short messages (tweets). - Users can follow/unfollow other users. - Home timel...
Design a recursive distributed file crawler
Design a distributed service that crawls a large file system starting from a root path. A client should be able to call an API to start a crawl job, a...
Design a digital game shop backend
Design the backend for a simple digital game shop where users can buy virtual items (e.g., games, in‑game currency, skins) using credits in their acco...
Design an airline booking system
System Design: Airline Booking System Design an airline booking platform that lets travelers search for flights, book them, select seats, and modify o...