KYC Service Low-Level Design: Identity Verification, Document Processing, and Compliance Workflow
6 min read What KYC Is and Why It's Hard Know Your Customer (KYC) is the process by which a business verifies the […] Read article
System Design
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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.
System Design
Feature Toggle Service Low-Level Design: Toggle Types, Targeting Rules, and Kill Switch
5 min read Why Feature Toggles? Feature toggles (also called feature flags or feature switches) decouple code deployment from feature release. You ship Read article
System Design
Job Coordinator Low-Level Design: DAG Execution, Dependency Tracking, and Failure Recovery
5 min read What a Job Coordinator Solves A job coordinator manages the execution of complex multi-step workflows where tasks have dependencies on Read article
System Design
Configuration Service Low-Level Design: Centralized Config, Hot Reload, and Environment Promotion
6 min read Why Centralize Configuration? Hardcoding configuration in application deployments creates operational problems: changing a timeout requires a redeploy, different environments diverge Read article
System Design
DNS Load Balancer Low-Level Design: Round-Robin DNS, Health-Aware Record Updates, and TTL Trade-offs
6 min read What Is DNS Load Balancing? DNS load balancing distributes client traffic across multiple servers by returning different IP addresses for Read article
System Design
Geo Routing Service Low-Level Design: IP Geolocation, Latency-Based Routing, and Failover
5 min read What a Geo Routing Service Does A geo routing service maps each incoming request to the most appropriate backend region Read article
System Design
Health Check Endpoint Low-Level Design: Liveness vs Readiness, Dependency Checks, and Aggregated Status
5 min read Why Health Check Endpoints Matter A health check endpoint gives orchestration platforms and load balancers a programmatic way to know Read article
System Design
Package Registry Low-Level Design: Artifact Storage, Version Resolution, and Dependency Graph
6 min read Package Registry: What It Solves A package registry is a versioned artifact store for software libraries. Developers publish packages; consumers Read article
System Design
CDN Edge Cache Low-Level Design: Cache Hierarchy, Origin Shield, Cache Invalidation, and Routing
6 min read CDN Edge Cache: What It Does A content delivery network (CDN) accelerates content delivery by caching responses at Points of Read article
System Design
Autoscaler Low-Level Design: Metric-Based Scaling, Cooldown Windows, and Predictive Scaling
6 min read Autoscaler: Core Responsibility An autoscaler dynamically adjusts the number of compute instances (replicas, pods, VMs) running a service based on Read article
System Design
Metrics Aggregation Service Low-Level Design: Time-Series Ingestion, Downsampling, and Query Engine
5 min read Metrics Aggregation: Purpose and Scope A metrics aggregation service collects numeric measurements from infrastructure and applications, stores them as time Read article
System Design
Alerting System Low-Level Design: Alert Evaluation, Deduplication, Routing, and On-Call Escalation
6 min read Alerting System: Goals and Challenges An alerting system monitors metrics and fires notifications when conditions violate defined thresholds. The central Read article
System Design
Web Crawler Low-Level Design: URL Frontier, Politeness Policy, and Distributed Crawl Coordination
6 min read Web Crawler: Core Architecture A web crawler fetches web pages at scale, extracts links, and feeds them back into the Read article
System Design
Order Management System Low-Level Design: Order State Machine, Inventory Reservation, and Fulfillment Coordination
5 min read Order State Machine An order progresses through a defined set of states with controlled transitions: CART → PLACED → PAYMENT_PENDING Read article
System Design
Sliding Window Counter Rate Limiter Low-Level Design: Hybrid Algorithm, Redis Sorted Sets, and Accuracy Trade-offs
5 min read Fixed Window Counter and Its Problem The simplest rate limiter increments a counter per time window and resets it at Read article