Mock Interview

Structured practice with progressive hints and self-evaluation.

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Design a real-time chat application supporting 1:1 messaging, group chats, and online presence indicators.

system-designintermediateAsked at Meta (WhatsApp/Messenger), Slack, Discord, and Microsoft

Design a notification system that can send push notifications, SMS, and emails at scale with user preferences and rate limiting.

system-designintermediateAsked at Amazon, Uber, Airbnb, and any platform with multi-channel notifications

Design a distributed rate limiter that can throttle API requests across multiple servers. Support different rate limiting strategies.

system-designintermediateCommon at Stripe, Cloudflare, AWS, and API-first companies

Design the home timeline feed for Twitter. Users should see tweets from people they follow, ordered by time or relevance.

system-designadvancedFrequently asked at Meta, Twitter/X, LinkedIn, and TikTok

Design a URL shortening service like bit.ly. It should generate short URLs, redirect users, and provide basic analytics.

system-designbeginnerCommon at Google, Meta, Amazon, and mid-stage startups

Design a web crawler that can crawl billions of web pages, extract content, and build a search index. Handle politeness, deduplication, and failures.

system-designadvancedFrequently asked at Google, Microsoft (Bing), and search-focused companies

Estimate the queries per second (QPS) that Uber's ride-matching service handles during peak hours in a major city.

estimationintermediate

Estimate the total storage YouTube needs for one year of video uploads, considering multiple resolutions and encoding formats.

estimationbeginner

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