Content Feed System Low-Level Design
Requirements Generate a personalized feed of posts ranked by relevance/recency for each user Supports follow relationships: see posts from users […]
Design, System Design
System Design
Learn to design scalable, reliable systems that handle millions of users. System design interviews test your ability to architect real-world applications, considering tradeoffs, scalability, and best practices.
Core Topics:
Scalability: Load balancing, horizontal vs vertical scaling
Storage: Databases (SQL vs NoSQL), caching (Redis, Memcached)
Reliability: Replication, failover, disaster recovery
Performance: CDNs, caching strategies, database indexing
Common Design Questions:
Design URL shortener (bit.ly)
Design rate limiter
Design Twitter/Instagram feed
Design messaging system (WhatsApp)
Design file storage (Dropbox)
Interview Level: Senior engineers (L5+) at FAANG companies. Requires 3-5+ years experience to tackle effectively.
Preparation: Study system design patterns, understand distributed systems fundamentals, and practice mock interviews.
Design, System Design
Online Auction System Low-Level Design
Requirements Users can create auction listings with a start price, reserve price, and end time Users place bids; highest bid
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Location Tracking System Low-Level Design
Requirements Track real-time location of mobile assets (drivers, delivery couriers, field workers) 1M active devices sending location updates every 4
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Data Pipeline System Low-Level Design
What is a Data Pipeline? A data pipeline is a sequence of data processing steps: collect → transform → store
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Coupon and Discount System Low-Level Design
Requirements Create and manage discount coupons (percentage, fixed amount, free shipping) Apply coupon to a cart: validate, compute discount, prevent
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Permission and Authorization System Low-Level Design
Permission Models Overview Three main models: ACL (Access Control List): per-resource list of who can do what. Simple, fine-grained, but
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Hotel Reservation System Low-Level Design
Requirements Search available rooms for a date range (check-in, check-out, guests, room type) Book a room: prevent double-booking the same
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Distributed Configuration Service Low-Level Design
What is a Distributed Configuration Service? A configuration service manages application settings, feature flags, and operational parameters across a distributed
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Task Queue System Low-Level Design
Requirements Producers enqueue tasks; workers process them asynchronously At-least-once delivery: tasks must not be lost on worker crash Retry with
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A/B Testing Platform Low-Level Design
What is A/B Testing? A/B testing (controlled experimentation) randomly assigns users to experimental variants and measures which variant produces better
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Fraud Detection System Low-Level Design
Requirements Detect fraudulent transactions in real time (<200ms per transaction decision) Flag suspicious user behavior: account takeover, card testing, synthetic
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Real-Time Analytics Platform Low-Level Design
Requirements Ingest billions of events per day (page views, clicks, transactions, errors) Support real-time dashboards with <10 second lag Support
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API Gateway Low-Level Design
What an API Gateway Does An API gateway is the single entry point for all client requests to a microservices
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Ad Click Tracker System Low-Level Design
Requirements Record every ad click event (ad_id, user_id, timestamp, ip, device_type) Query click counts per ad for any time range
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Game Leaderboard System Low-Level Design
Requirements Update a player score in real time Query the global top-100 leaderboard Query a player’s exact rank among all