Content Feed System Low-Level Design
6 min read Requirements Generate a personalized feed of posts ranked by relevance/recency for each user Supports follow relationships: see posts from users […] Read article
System Design
System Design
Search Suggestions (Autocomplete) System Low-Level Design
6 min read Requirements Return top-k (k=10) query suggestions as a user types, within 100ms Suggestions ranked by search frequency or relevance score Read article
System Design
Location Tracking System Low-Level Design
6 min read Requirements Track real-time location of mobile assets (drivers, delivery couriers, field workers) 1M active devices sending location updates every 4 Read article
System Design
Data Pipeline System Low-Level Design
6 min read What is a Data Pipeline? A data pipeline is a sequence of data processing steps: collect → transform → store Read article
Algorithms, Coding Interview Questions, Data Structures
Ordered Map (TreeMap / SortedList) Interview Patterns
6 min read When to Use an Ordered Map (Sorted Dict / TreeMap) An ordered map maintains keys in sorted order with O(log Read article
System Design
Permission and Authorization System Low-Level Design
6 min read Permission Models Overview Three main models: ACL (Access Control List): per-resource list of who can do what. Simple, fine-grained, but Read article
System Design
Coupon and Discount System Low-Level Design
6 min read Requirements Create and manage discount coupons (percentage, fixed amount, free shipping) Apply coupon to a cart: validate, compute discount, prevent Read article
Algorithms, Coding Interview Questions, String Manipulation
String Hashing Interview Patterns
6 min read Why String Hashing? Naive string comparison is O(L) per comparison where L is the string length. String hashing converts a Read article
System Design
Distributed Configuration Service Low-Level Design
6 min read What is a Distributed Configuration Service? A configuration service manages application settings, feature flags, and operational parameters across a distributed Read article
System Design
Hotel Reservation System Low-Level Design
6 min read Requirements Search available rooms for a date range (check-in, check-out, guests, room type) Book a room: prevent double-booking the same Read article
Algorithms, Coding Interview Questions
Two Pointers Advanced Interview Patterns
6 min read When to Use Two Pointers Two pointers reduce O(n²) brute force to O(n) or O(n log n) by exploiting sorted Read article
System Design
A/B Testing Platform Low-Level Design
6 min read What is A/B Testing? A/B testing (controlled experimentation) randomly assigns users to experimental variants and measures which variant produces better Read article
System Design
Task Queue System Low-Level Design
6 min read Requirements Producers enqueue tasks; workers process them asynchronously At-least-once delivery: tasks must not be lost on worker crash Retry with Read article
Algorithms, Coding Interview Questions
Bit Manipulation Interview Patterns
6 min read Essential Bit Operations x & y # AND: both bits must be 1 x | y # OR: at least Read article
System Design
Real-Time Analytics Platform Low-Level Design
6 min read Requirements Ingest billions of events per day (page views, clicks, transactions, errors) Support real-time dashboards with <10 second lag Support Read article