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 scalable worker pool for template jobs
You have implemented a function that takes a template string (or many template strings) and replaces placeholders like {{db_host}} and {{db_port}} usi...
4.1 Design a Live Streaming Platform
This is a classic system design question that tests your ability to handle real-time data at massive scale. Live streaming sits at the intersection of...
Design in-memory delivery billing core APIs
You are asked to design an in-memory billing service for a food-delivery platform. The focus is on data structures and API behavior; you may ignore pe...
Design 64-bit distributed IDs and a parking lot
You have two system-design prompts. 1) 64-bit database ID generator Design a service/library that generates globally unique 64-bit integer IDs for dat...
Design KV store with sliding-window QPS metrics
Problem Design an in-memory key–value store that supports basic operations and can report the average operation load over a recent time window. Functi...
Design a search-to-ads ranking pipeline
Prompt Design a high-level search + ads ranking system for an app where a user issues a query and the product shows a mix of organic search results an...
Design ads frequency capping service
Design an Ads Frequency Capping Service Context You are designing a service that ensures a user does not see the same ad creative or campaign more tha...
Implement a leaky-bucket rate limiter
Implement a Leaky-Bucket Rate Limiter with Tests and Distributed Design Context and Assumptions - Implement in a general-purpose language; the referen...
Design a scalable resume search system
System Design: Resume Search Platform Context A recruiting company needs a platform where applicants can upload resumes and recruiters can search, fil...
Design a fair event registration queue API
Scenario Design an in-memory service (OOD-style) to manage registrations for an event where fairness means users are served strictly in the order they...
Design a search query autocomplete system
Question Design a search autocomplete system that suggests completions as the user types. Requirements - Sub-100ms latency per keystroke. - Suggestion...
Design a loan application system
System Design: End-to-End Online Loan Application Platform Context Design a small online lending platform where applicants select loan products and su...
Design a Data Stream Processor
Design a real-time data stream processing system for application events. Each incoming event contains fields such as event_id, creator_id, event_type,...
Design an in-memory hotel booking system
Design a hotel booking system that supports reservations without using any database. You may only use in-memory data structures. Requirements Define A...
Design config rollout and click aggregation
The system design rounds included two prompts: 1. Global configuration deployment - Design a system that allows engineers to publish configuration ...
Enable secure offline reservation caching
System Design: Offline Caching for Reservations (PWA) Design a web application that supports offline access to reservation information. The app is a p...
Implement a minimal local HTTP server
Build a Minimal Local HTTP/1.1 Server (No Frameworks) Context You are asked to implement a minimal HTTP/1.1 server from scratch using only the standar...
Design task scheduler with dependencies
Design a Distributed Task Scheduling Infrastructure Context Design a distributed task scheduling and orchestration system that can run at scale, suppo...
Design a scalable, reliable system
System Design: Global Photo/Video File Storage and Sharing ("CloudDrive") Context Design a scalable, highly reliable consumer service where users uplo...
Design async batched key-value fetcher
Design an async, batched key-value fetcher with a 100 ms window Context You have a single-threaded, event-loop environment (e.g., JS/TS). A backend en...