System Design Interview Questions
Practice 968 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 content moderation system
Design a content moderation system for a large-scale product where users can submit content (e.g., text posts, images, videos, comments, or messages)....
Design read-heavy org chart subordinate counts
You are given manager→direct-report relationships for an organization (an employee has at most one direct manager; the top-level employee has none). B...
Design a distributed web crawler
Problem Design a web crawler that starts from one or more seed URLs and continuously discovers and fetches pages. Requirements - Inputs: One or more s...
Design real-time modules communication and overload handling
You are designing a real-time system running on a single machine with two modules (e.g., producer -> consumer) that must communicate with low latency....
Design reliable high-volume chatbot system
You are designing the backend for a chatbot / AI assistant service (similar to a support bot or meeting assistant). Many users may send messages at th...
Design scheduled payments and cancellation
Question Design a scheduled payments service for Coinbase that lets users create, list, update, execute, and cancel future-dated payments — both one-t...
Design review system with voting and rewards
Design: Scalable Product Reviews with Voting and Rewards Context You are designing a reviews feature for a large e-commerce marketplace. Customers can...
Design resilient auth with flaky third-party tokens
System Design: Resilient, Secure Request Flow with Unreliable Third‑Party Authorization Context You are designing a multi‑region, HTTP/JSON API where ...
Design a scalable network I/O service
System Design: High-Volume Network I/O Backend (Files and Streaming) Context Design a backend service that supports millions of users uploading and do...
Explain Kafka partitions and delivery semantics
Kafka partitions, replication, consumer groups, and delivery guarantees Context You are designing and evaluating a Kafka-based data pipeline and need ...
Design JSON serialization for circular references
Design a JSON Serialization/Deserialization Strategy With Cycles and Determinism You are designing a JSON-based serializer/deserializer for a graph of...
Design a Production-Ready URL Shortener
System Design: Production-Ready URL Shortening Service Goal Design a production-ready URL shortening service that can issue short links, resolve them ...
Design a One-to-One Chat System
Design a real-time one-to-one chat system. Requirements: - Registered users must authenticate before connecting. - After authentication, clients keep ...
Design Flight Booking and Voting Systems
Answer both system design prompts. Part A: Flight Ticket Booking System Design the backend for a flight ticket booking product. The system should supp...
Design a Real-Time Monitoring System
Design a real-time monitoring system for a large production environment. The system should: - collect time-series metrics such as CPU, memory, request...
Fix and harden an object pool
Refactor a Buggy C++ Object Pool Into a Correct, Thread-Safe Template Context You are given a buggy C++ object pool that suffers from races, double-fr...
Design backend to score and classify tweets
You are asked to build a small backend application that processes Twitter data and uses an external LLM-style API to score and classify each tweet. Re...
Design a scalable recommendation serving system
Scenario You are designing the online serving infrastructure for a large-scale recommendation system (e.g., a delivery app or e-commerce feed). The in...
Design a file search module like UNIX find
Design Task: Object-Oriented module that mimics UNIX find Context Design an object-oriented library that replicates the core functionality of the UNIX...
Design a thread-safe high-QPS rate limiter
Question You are building a backend service that must enforce API rate limits. Design and (at a high level) implement a rate limiter, then work throug...