DNS Resolver and DNS System Design
7 min read What Does a DNS Resolver Do? The Domain Name System (DNS) translates human-readable domain names (www.example.com) into IP addresses (93.184.216.34). […] Read article
System Design
System Design
Referral System Low-Level Design
7 min read Requirements Users share a unique referral code or link to invite new users Referrer earns a reward when a referred Read article
System Design
Feature Store System Low-Level Design
7 min read What is a Feature Store? A feature store is a centralized repository for ML features. It solves the “feature engineering Read article
System Design
Dead Letter Queue (DLQ) System Low-Level Design
7 min read What is a Dead Letter Queue? A Dead Letter Queue (DLQ) holds messages that could not be processed successfully after Read article
System Design
Loyalty Program System Low-Level Design
6 min read Requirements Earn points on purchases and specific actions (sign-up, referral, review) Redeem points for discounts, rewards, or free items Tiered Read article
System Design
Event Sourcing System Low-Level Design
7 min read What is Event Sourcing? In a traditional system, the database stores the current state: “Account balance = $500.” In event Read article
System Design
Session Management System Low-Level Design
6 min read What is Session Management? Session management maintains the authenticated state of a user across multiple HTTP requests. HTTP is stateless Read article
System Design
Comment System Low-Level Design
7 min read Requirements Users can post comments on content items (posts, videos, products) Threaded replies (nested comments) up to N levels deep Read article
System Design
Cache System Low-Level Design (LRU, Write Policies, Redis Cluster)
7 min read Why Caching? A cache stores copies of frequently-accessed data in fast storage (RAM) to avoid expensive re-computation or round trips Read article
System Design
Email Delivery System Low-Level Design
7 min read Requirements Send transactional emails (password reset, order confirmation, notifications) and marketing emails (campaigns, newsletters) 100M emails/day, peak 10K/second during campaigns Read article
System Design
CI/CD Pipeline System Low-Level Design
7 min read What is a CI/CD Pipeline? CI (Continuous Integration): automatically build and test code on every commit. CD (Continuous Delivery/Deployment): automatically Read article
Algorithms, Coding Interview Questions, Heap
Two Heaps Interview Pattern
6 min read The Two Heaps Pattern Two heaps maintain the lower and upper halves of a data stream, allowing O(1) access to Read article
System Design
Secret Manager System Low-Level Design
7 min read What is a Secret Manager? A secret manager stores and distributes sensitive credentials (API keys, database passwords, TLS certificates, OAuth Read article
System Design
Log Aggregation System Low-Level Design
6 min read What is a Log Aggregator? A log aggregator collects logs from distributed services, normalizes them, stores them for search, and Read article
Algorithms, Coding Interview Questions, Data Structures
Matrix Traversal Interview Patterns
7 min read Grid Traversal Fundamentals Most matrix problems involve: (1) BFS from one or multiple source cells, (2) DFS to explore connected Read article