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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Design a Food Rating System
Design a rating and review system for a food delivery marketplace (e.g. DoorDash). Users of the system should be able to: - Rate a food item on a fixe...
Design a Task Scheduler for Opaque Long-Running GPU Jobs ("Design Sora")
Design a task scheduler that runs long-running, opaque video-generation jobs at scale (the "Design Sora" prompt). Your platform lets users submit a te...
Design a Resilient Document Aggregation Service
Design a Resilient Document Aggregation Service Your team owns a backend service that assembles a "document bundle" for clients. To build one bundle, ...
Design GPU Scheduling for a Video Generation Platform
Design GPU scheduling for a video generation platform where requests have different durations, priorities, and capacity needs. <details> <summary>Hint...
Design a Distributed Key-Value Store
Design a horizontally scalable distributed key-value store. The system stores opaque values keyed by a string key and supports get, put, and delete on...
Design a Ride-Sharing System (Uber-style Core Platform)
Design a Ride-Sharing System (Uber-style Core Platform) Design the core backend of a ride-sharing platform like Uber. Riders open the app, see nearby ...
Design A ChatGPT-Style Assistant Product
Design a ChatGPT-style assistant product. Cover the user experience, conversation state, message streaming, model invocation, safety and error handlin...
Design a Real-Time Chat System
Design a Real-Time Chat System Design the backend for a real-time one-to-one and group messaging application (think a 1:1 and small-group chat product...
Design a Distributed File System
Design a distributed file system for a cloud service — a POSIX-like storage layer that internal applications and external customers use to store and r...
Design an Ad Pacing System
Design an advertising pacing system for a large-scale video / streaming advertising platform. Advertisers create campaigns with budgets, flight dates ...
Design a Metrics Ingestion Pipeline
Design a metrics ingestion pipeline for a large engineering organization. Thousands of services running across tens of thousands of hosts emit operati...
Externally Sort a 500 GB CSV by One Column with 16 GB of RAM
You are handed a single very large CSV file (roughly 500 GB) sitting on the local disk of one machine. The machine has only about 16 GB of usable RAM....
Design a Local Leader Election System
Design and implement a local leader–follower distributed system. You have several nodes running on a single machine, each as a separate process (or se...
Design Top-K, Crawler, and Chess Systems
During a senior software engineering virtual onsite, you are given three independent, traditional system design prompts. Treat each one as a separate ...
Design A Drive-Style Usage Quota Limiter
Design a quota limiter for a cloud storage product similar to a drive service. The system should enforce usage limits while users upload, modify, or d...
Design Ad Frequency and Order Tracking
Design two components of an ads platform. This is a two-part system-design question: Part 1 is a real-time frequency-capping service used during ad de...
Design a Distributed Metrics Counter
Design a distributed metrics counter service for internal product telemetry. The service should support: - increment(metric_name, delta, tags, timesta...
Design Food Ratings and Driver Payouts
Design the backend for a food-delivery product (think DoorDash-style marketplace). The system has two distinct surfaces that you must address together...
Design an Ad Assignment API
Design an HTTP API that exposes an ad-assignment function as a production service. The underlying function is given a user, a list of browser position...
Design Search And Web Crawling Systems
You are asked to design two distinct large-scale systems in a single system-design interview loop: a Facebook-like search product and a distributed we...