Senior+ System Design Interview Questions
System design is the round that carries the most weight in a senior+ loop, and it's where senior+ candidates most often pass or fail. These system design questions were reported from senior-level interviews, so they reflect what interviewers actually push on at the senior+ bar: designing for scale, reasoning explicitly about trade-offs, handling failure modes, and driving the conversation instead of waiting to be led. Expect open-ended prompts — design a rate limiter, a news feed, a notification system — where the interviewer probes your bottlenecks and asks you to defend every decision. Each comes with a detailed model answer that walks through requirements, the high-level design, the deep dives, and the trade-offs a strong senior+ answer makes explicit.
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"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."
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"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."
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Design a large-scale distributed rate limiter
This question evaluates system design competency in distributed systems, focusing on scalability, multi-tenant isolation, rate-limiting algorithms, co...
Defend a Data Pipeline Architecture and Its Trade-offs
Prompt Choose one production data pipeline that you personally designed or substantially changed. Walk through its architecture, the requirements that...
Design an online auction system
Design a scalable online auction service. Users can: - Create an auction (item info, start/end time, reserve price optional). - Place bids while the a...
Design a typeahead search service
Design a search autocomplete system for a large application. As a user types a prefix, the system should return relevant suggestions with low latency....
Design bookstore and chat messaging systems
This question evaluates a candidate's competency in large-scale system design, including distributed systems architecture, data modeling, consistency ...
Design and implement an Airbnb wallet
Design and Implement an Airbnb-Style Wallet (OOD + Runnable Code) You are asked to design and implement an in-app wallet system for a marketplace like...
Design Real-Time Auctions for Social Posts
Design a real-time auction feature for a large social photo and video app. A creator can attach an auction to a post. Viewers can place bids, and ever...
Design a Reliable URL Shortening Service
Design a Reliable URL Shortening Service Design a service that accepts a long URL and returns a short URL, then redirects short-code requests to the s...
Design a global real-time notification system
This question evaluates competency in designing large-scale distributed systems for global real-time notifications, covering scalability, multi-region...
Design consistent hashing for sharding
Design a Consistent-Hashing Router with Replication You are building a stateless router that maps arbitrary keys (for example, request IDs or cache ke...
Design Queue And Taxi Matching Services
Answer both independent system design prompts. For each one, clarify requirements, propose APIs, describe core data models, explain the architecture, ...
Design a replicated key-value store with quorums
Design a distributed system that replicates key–value pairs across multiple replicas. The interviewer wants to focus on replication, quorums, and fail...
Design an ads data model
This question evaluates a candidate's ability to design scalable data models and system architecture for an ads platform, including entity relationshi...
Design Internal Chat and Re-engagement Emails
Design an internal chat system for an event marketplace company. Requirements: - Employees can send and receive one-to-one messages in real time. - Cl...
Design first-time Kubernetes deployment in new cloud
This question evaluates system design and cloud platform engineering skills focused on first‑time Kubernetes deployment, covering account bootstrappin...
Design a Top-K trending items service
This question evaluates competency in large-scale system design, real-time streaming ingestion, distributed aggregation, and trade-offs between exact ...
Design an Online Coding Judge
This question evaluates system design and scalability skills for building a high-throughput, low-latency online coding judge, covering distributed arc...
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 a Metrics Storage Platform
This question evaluates system-design and distributed-systems skills for time-series metrics storage, focusing on data modeling for counters, gauges, ...
Design Frontend Architecture for Trading UI
Design the frontend architecture for a production trading system UI. Assume the product is a web trading interface with areas such as a market chart, ...