System Design Interview Questions

System design interviews test your ability to architect large-scale systems under constraints. These questions cover the core scenarios interviewers ask at every level — from designing a URL shortener to building a real-time notification system. Each question includes a structured approach, key tradeoffs to discuss, and the depth interviewers expect at different seniority levels.

5 questions • 4 categories • Updated March 2026

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Classic Problems

Mid-Level 8 min

Design a URL Shortener (System Design Interview)

Design a URL shortening service like bit.ly. It should generate short URLs, redirect users, and handle high traffic.

Infrastructure

Mid-Level 7 min

Design a Rate Limiter (System Design Interview)

Design a rate limiter that can be used as middleware for an API. It should support different rate limits per user and per endpoint.

Communication Systems

Senior 9 min

Design a Notification System (System Design Interview)

Design a notification system that supports push notifications, email, SMS, and in-app notifications for millions of users.
Senior 9 min

Design a Real-Time Chat System (System Design Interview)

Design a real-time chat system that supports one-on-one messaging, group chats, online presence, and message delivery receipts.

Storage Systems

Senior 10 min

Design a Distributed Key-Value Store (System Design Interview)

Design a distributed key-value store that supports get(key) and put(key, value) with high availability and partition tolerance.