Low Level Design: LFU Cache
8 min read Core Problem LFU (Least Frequently Used) is a cache eviction policy that removes the item with the lowest access frequency […] Read article
System Design
System Design
Low Level Design: Skip List
6 min read Structure A skip list is a probabilistic data structure that maintains a sorted collection and supports O(log N) expected time Read article
System Design
Low Level Design: Healthcare Appointment Booking System
10 min read Provider Schedule Model A provider’s schedule is defined at two levels: recurring availability rules and date-specific overrides. Recurring rules describe Read article
System Design
Low Level Design: Smart Home System
11 min read Home Hub Architecture The home hub is the central controller for all smart home devices in a physical residence. Deployed Read article
System Design
Low Level Design: Configuration Management System
9 min read Config Data Model A configuration management system stores each configuration entry as a structured record with the following fields: key Read article
System Design
Low Level Design: Shopping Cart System
9 min read Cart Storage Options There are three main approaches to storing a shopping cart. Client-side storage keeps the cart in the Read article
System Design
Low Level Design: Fraud Detection System
9 min read Real-Time Scoring Pipeline Every transaction enters the fraud scoring pipeline synchronously before a payment decision is returned. The flow: transaction Read article
System Design
Low Level Design: Digital Wallet System
9 min read Double-Entry Accounting A digital wallet is a ledger, and the correct foundation for any ledger is double-entry accounting. Every financial Read article
System Design
Low Level Design: Ride-Hailing Dispatch System
10 min read Driver State Machine Every driver in the system exists in one of four states: offline, available, on_trip, or returning. The Read article
System Design
Low Level Design: Machine Learning Platform
8 min read Training Job Orchestration A training job submission API accepts the full specification of a run: the training script path, the Read article
System Design
Low Level Design: Circuit Breaker Pattern
9 min read State Machine The circuit breaker is a three-state machine wrapped around each outbound call to a downstream dependency. In the Read article
System Design
Low Level Design: Ticket Booking System
9 min read Ticket booking systems handle some of the most demanding concurrency scenarios in software engineering. When a popular concert goes on Read article
System Design
Low Level Design: Calendar and Scheduling System
9 min read Calendar and scheduling systems look deceptively simple on the surface but contain significant engineering depth. Recurring events, timezone transitions, multi-user Read article
System Design
Low Level Design: Poll and Voting System
9 min read Poll and voting systems appear in everything from social media reactions to high-stakes organizational decisions. The engineering challenges span idempotent Read article
System Design
Low Level Design: Map and Navigation System
6 min read Road Graph Storage A map is modeled as a directed weighted graph. Nodes represent intersections and road endpoints, each storing Read article