How difficult are system design interview questions and what levels do they correspond to?

System design questions span a wide difficulty spectrum: at entry and junior levels they focus on clear scoping, simple data models, basic APIs, and single-service scaling; at mid levels expect capacity estimation, sharding, caching, and asynchronous pipelines; at senior and staff levels interviewers probe multi-region architectures, consistency tradeoffs, operational reliability, cost/latency tradeoffs, and end-to-end failure modes. In 2026 many teams also test GenAI/LLM system thinking like inference orchestration and retrieval pipelines. Difficulty depends on role and level, so expect depth and breadth to increase with seniority.

Where in the interview loop does system design typically appear and which companies use it most?

System design usually appears as one or more dedicated technical rounds during onsites or virtual loops, often paired with coding and behavioral interviews. Large product companies and platform teams at Meta, Amazon, Google, and DoorDash include system design for mid-to-senior SWE roles; OpenAI and other AI-first companies add design scenarios specific to model serving, data privacy, and inference cost. Roles tested include Software Engineer, SRE, ML/MLinfra, and Data Engineer. The exact placement varies by company and level: some firms push design earlier for stronger product alignment, others reserve it for final onsite interviews.

How much time should I spend preparing for system design interviews and what timeline works best?

A focused 6–12 week plan suits most candidates: weeks 1–2 review core concepts (distributed systems fundamentals, caching, databases, networking), weeks 3–6 practice canonical designs and build templates for common problems, weeks 7–9 deep-dive into tricky areas you expect per target company (e.g., LLM inference at OpenAI, high-write workloads at DoorDash), and weeks 10–12 run timed mock interviews with feedback and iterate. If you’re senior, allocate extra time to design tradeoffs, operational runbooks, and cross-team communication exercises. Consistent, feedback-driven practice matters more than raw hours.

What key subtopics and technical concepts should I master for system design interviews?

Master requirement elicitation, API and data model design, capacity and latency estimation, load balancing, caching strategies, data partitioning and sharding, consistency models, replication, message queues, background processing, rate limiting, and monitoring/alerting. Also know storage options and tradeoffs, CDN usage, and cost-performance reasoning. In 2026 add GenAI-specific concepts: model hosting, batching and batching-latency tradeoffs, vector stores, retrieval-augmented generation, privacy and safe-guarding pipelines, and model-versioning. Be prepared to justify tradeoffs and relate them to metrics and operational realities.

What standout tips and common pitfalls should I know to improve my system design performance?

Start by clarifying goals and constraints, then outline a high-level architecture before diving into components. Use concrete metrics and back-of-envelope capacity calculations to justify choices. Favor incremental designs that can evolve and explain tradeoffs between latency, cost, and consistency. Discuss failures, recovery, monitoring, and testing plans. Common pitfalls include over-engineering, skipping requirement scoping, ignoring operational burdens, and failing to state assumptions. For AI-focused designs, explicitly address data privacy, model drift, and cost of inference. Practice verbalizing decisions; interviews are conversational design exercises, not monologues.

System Design Interview Questions (Updated 2026)

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.

Questions

981

Companies

215

Updated

06.24.2026

981 Questions 215 Companies06.24.2026

PLTCHK

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_The_TaNk_

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ChrisSenior SWE, LinkedIn

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sleepy33

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JakeSenior ML Engineer, Lyft

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nuggetlord

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CarlosFull Stack, Shopify

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boba.tea.vibes

"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."

AndySWE-II, Google

"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."

couchpotato99

"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."

ShrutiData Engineer, Salesforce

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midnightramen

"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."

BiancaFrontend Eng, Figma

"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."

tambrahm007

"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."

toa

"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."

PLTCHK

_The_TaNk_

ChrisSenior SWE, LinkedIn

"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."

sleepy33

"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."

JakeSenior ML Engineer, Lyft

"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."

nuggetlord

CarlosFull Stack, Shopify

"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."

boba.tea.vibes

"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."

AndySWE-II, Google

"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."

couchpotato99

"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."

ShrutiData Engineer, Salesforce

"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."

midnightramen

"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."

BiancaFrontend Eng, Figma

"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."

tambrahm007

"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."

toa

"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."

Showing 20 results

Role

System Design Interview Questions

Design a Distributed Rate Limiter

Design a prompt playground

Design a One-on-One Chat Service

Design a Security Monitoring Framework

Design a Food Rating System

Design an Instagram-like Feed System

Design Video Generation Orchestration

Design a Shared Calendar Service

Design a Superhero Dispatch System

Design a Distributed Crossword Solver

Prevent Duplicate Payments Under High Load

Design Online Chess Matchmaking

Design CI/CD Build Caching

Design a Book Price Aggregator

Design Multi-Dimensional Request Rate Limiting

Design a Log Collection System

Design a Played-By Summary System

Design ad frequency capping

Design a chargeback ingestion and export system

Design Crypto Order Routing

Frequently Asked Questions