System Design interview questions
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Walk me through your framework for approaching any system design interview.
Easy · System Design, Framework & Fundamentals
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How do you gather requirements — functional vs non-functional? What NFRs must you always cover?
Easy · System Design, Framework & Fundamentals
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Show back-of-the-envelope estimation for a large-scale system (traffic, storage, bandwidth, cache, servers).
Easy · System Design, Framework & Fundamentals, Capacity Estimation
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Explain CAP and PACELC. How do you pick between consistency and availability in real systems?
Medium · System Design, Framework & Fundamentals, Consistency & Consensus
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Walk through the scalability journey — vertical, horizontal, sharding, replication, async, CDN.
Medium · System Design, Framework & Fundamentals, Building Blocks
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How do you talk about trade-offs during a system design interview?
Easy · System Design, Framework & Fundamentals
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What are the most common mistakes candidates make in system design interviews, and how do you avoid them?
Easy · System Design, Framework & Fundamentals
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How do you choose the tech stack during a system design interview?
Easy · System Design, Framework & Fundamentals, Cloud & Deployment
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Design and place load balancers — L4 vs L7, algorithms, global vs regional.
Medium · System Design, Building Blocks
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Explain caching strategies — cache-aside, read/write-through, write-behind, TTL, invalidation.
Medium · System Design, Building Blocks, Caching & CDN
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Explain consistent hashing with virtual nodes. Where is it used in production?
Medium · System Design, Building Blocks, Databases & Storage
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Given an access pattern, walk through choosing between SQL / KV / Document / Wide-column / Search / Graph / Vector.
Medium · System Design, Databases & Storage, Building Blocks
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SQL vs NoSQL vs NewSQL — go beyond the buzzwords.
Medium · System Design, Databases & Storage
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REST vs GraphQL vs gRPC — when to choose which.
Medium · System Design, Building Blocks
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Implement idempotency for a POST /transfer API correctly.
Medium · System Design, Building Blocks, Payments & Fintech
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How do you design reliable webhooks / async callbacks?
Medium · System Design, Building Blocks, Messaging & Streaming
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Design a distributed rate limiter.
Medium · System Design, Product Design, Building Blocks
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Design a distributed key-value store (Dynamo-style).
Hard · System Design, Product Design, Databases & Storage
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Design a unique ID generator (Snowflake-style).
Medium · System Design, Product Design, Building Blocks
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Design a URL shortener (bit.ly / TinyURL).
Medium · System Design, Product Design
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Design a web crawler (Googlebot-scale).
Hard · System Design, Product Design, Search & Ads
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Design a large-scale notification system (push, SMS, email).
Medium · System Design, Product Design, Messaging & Streaming
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Design a news feed (Twitter / Facebook home timeline).
Hard · System Design, Product Design, Social & Feed
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Design a real-time chat system (WhatsApp / Messenger).
Hard · System Design, Product Design, Communication Products
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Design search autocomplete (Google / Amazon suggest).
Medium · System Design, Product Design, Search & Ads
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Design YouTube — upload, transcode, and adaptive streaming.
Hard · System Design, Product Design, Media & Streaming
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Design Google Drive / Dropbox — file sync + share.
Hard · System Design, Product Design, Storage Products
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Design a proximity service (Yelp / Nearby).
Medium · System Design, Product Design, Location & Maps
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Design Nearby Friends / live location sharing.
Medium · System Design, Product Design, Location & Maps
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Design Google Maps.
Hard · System Design, Product Design, Location & Maps
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Design a distributed message queue (Kafka-style).
Hard · System Design, Product Design, Messaging & Streaming
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Design a metrics + monitoring platform.
Hard · System Design, Product Design, Reliability & Observability
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Design an ad-click aggregation / real-time analytics system.
Hard · System Design, Product Design, Search & Ads
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Design a hotel reservation system.
Hard · System Design, Product Design
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Design an object storage service (S3-like).
Hard · System Design, Product Design, Storage Products
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Design a payment system.
Hard · System Design, Product Design, Payments & Fintech
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Design a digital wallet (PayPal / Paytm).
Hard · System Design, Product Design, Payments & Fintech
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Design a real-time gaming leaderboard.
Medium · System Design, Product Design
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Design a stock exchange / order matching engine.
Hard · System Design, Product Design, Payments & Fintech
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Design a RAG (Retrieval-Augmented Generation) platform end-to-end.
Hard · System Design, AI & ML Systems
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Design an ML inference / model serving platform (SageMaker-style).
Hard · System Design, AI & ML Systems, Cloud & Deployment
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Design a vector similarity search system for 1B+ vectors.
Hard · System Design, AI & ML Systems, Databases & Storage
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Multi-region architecture — active-active vs active-passive; how to choose?
Hard · System Design, Cloud & Deployment, Architect-Level
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How do you deploy your system design on Kubernetes end-to-end?
Medium · System Design, Cloud & Deployment
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Design a full observability stack — metrics, logs, traces, SLOs.
Medium · System Design, Reliability & Observability
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Walk through security & defence-in-depth for a modern cloud system.
Medium · System Design, Security & Privacy, Cloud & Deployment
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How would you optimise cost for a large-scale cloud system?
Medium · System Design, Cloud & Deployment, Architect-Level
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Testing strategy for a large distributed system — unit → contract → chaos.
Medium · System Design, Reliability & Observability
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Design a zero-downtime database migration playbook.
Hard · System Design, Databases & Storage, Cloud & Deployment
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Explain cell-based architecture (AWS / Slack / Datadog blueprint).
Hard · System Design, Architect-Level
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Event-driven architecture — patterns, outbox, saga, DLQ.
Hard · System Design, Architect-Level, Messaging & Streaming
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CQRS + Event Sourcing — when, how, and pitfalls.
Hard · System Design, Architect-Level
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Service mesh (Istio / Linkerd) — when it earns its cost.
Hard · System Design, Architect-Level, Cloud & Deployment
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Design a multi-tenant SaaS platform — isolation, RLS, quotas, billing.
Hard · System Design, Architect-Level, Cloud & Deployment
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Implement a rate limiter using Redis (deep-dive on Lua scripts and cluster behaviour).
Medium · System Design, Building Blocks, Messaging & Streaming