All Articles (14 articles)

  • Design Real-Time Chat and Messaging

    System Design / System Design Problems 21 min read

    A comprehensive system design for real-time chat and messaging covering connection management, message delivery guarantees, ordering strategies, presence systems, group chat fan-out, and offline synchronization. This design addresses sub-second message delivery at WhatsApp/Discord scale (100B+ messages/day) with strong delivery guarantees and mobile-first offline resilience.

  • Design Uber-Style Ride Hailing

    System Design / System Design Problems 23 min read

    A comprehensive system design for a ride-hailing platform handling real-time driver-rider matching, geospatial indexing at scale, dynamic pricing, and sub-second location tracking. This design addresses the core challenges of matching millions of riders with drivers in real-time while optimizing for ETAs, driver utilization, and surge pricing across global markets.

  • Design Search Autocomplete: Prefix Matching at Scale

    System Design / System Design Problems 18 min read

    A system design for search autocomplete (typeahead) covering prefix data structures, ranking algorithms, distributed architecture, and sub-100ms latency requirements. This design addresses the challenge of returning relevant suggestions within the user’s typing cadence—typically under 100ms—while handling billions of queries daily.

  • Design a Web Crawler

    System Design / System Design Problems 29 min read

    A comprehensive system design for a web-scale crawler that discovers, downloads, and indexes billions of pages. This design addresses URL frontier management with politeness constraints, distributed crawling at scale, duplicate detection, and freshness maintenance across petabytes of web content.

  • Design Google Search

    System Design / System Design Problems 25 min read

    Building a web-scale search engine that processes 8.5 billion queries daily across 400+ billion indexed pages with sub-second latency. Search engines solve the fundamental information retrieval problem: given a query, return the most relevant documents from a massive corpus—instantly. This design covers crawling (web discovery), indexing (content organization), ranking (relevance scoring), and serving (query processing)—the four pillars that make search work at planetary scale.

  • Design Collaborative Document Editing (Google Docs)

    System Design / System Design Problems 19 min read

    A comprehensive system design for real-time collaborative document editing covering synchronization algorithms, presence broadcasting, conflict resolution, storage patterns, and offline support. This design addresses sub-second convergence for concurrent edits while maintaining document history and supporting 10-50 simultaneous editors.

  • Design Dropbox File Sync

    System Design / System Design Problems 16 min read

    A system design for a file synchronization service that keeps files consistent across multiple devices. This design addresses the core challenges of efficient data transfer, conflict resolution, and real-time synchronization at scale—handling 500+ petabytes of data across 700 million users.

  • Design Google Calendar

    System Design / System Design Problems 23 min read

    A comprehensive system design for a calendar and scheduling application handling recurring events, timezone complexity, and real-time collaboration. This design addresses event recurrence at scale (RRULE expansion), global timezone handling across DST boundaries, availability aggregation for meeting scheduling, and multi-client synchronization with conflict resolution.

  • Design an Issue Tracker (Jira/Linear)

    System Design / System Design Problems 27 min read

    A comprehensive system design for an issue tracking and project management tool covering API design for dynamic workflows, efficient kanban board pagination, drag-and-drop ordering without full row updates, concurrent edit handling, and real-time synchronization. This design addresses the challenges of project-specific column configurations while maintaining consistent user-defined ordering across views.

  • Design a Payment System

    System Design / System Design Problems 24 min read

    Building a payment processing platform that handles card transactions, bank transfers, and digital wallets with PCI DSS compliance, idempotent processing, and real-time fraud detection. Payment systems operate under unique constraints: zero tolerance for duplicate charges, regulatory mandates (PCI DSS), and sub-second fraud decisions. This design covers the complete payment lifecycle—authorization, capture, settlement—plus reconciliation, refunds, and multi-gateway routing.

  • Design a Flash Sale System

    System Design / System Design Problems 23 min read

    Building a system to handle millions of concurrent users competing for limited inventory during time-bounded sales events. Flash sales present a unique challenge: extreme traffic spikes (10-100x normal) concentrated in seconds, with zero tolerance for inventory errors. This design covers virtual waiting rooms, atomic inventory management, and asynchronous order processing.

  • Design Amazon Shopping Cart

    System Design / System Design Problems 22 min read

    A system design for an e-commerce shopping cart handling millions of concurrent users, real-time inventory, dynamic pricing, and distributed checkout. This design focuses on high availability during flash sales, consistent inventory management, and seamless guest-to-user cart transitions.

  • URL Shortener Design: IDs, Storage, and Scale

    System Design / System Design Problems 1 min read

    A comprehensive guide to designing a scalable URL shortening service like bit.ly or TinyURL.

  • Design a Cookie Consent Service

    System Design / System Design Problems 25 min read

    Building a multi-tenant consent management platform that handles regulatory compliance (GDPR, CCPA, LGPD) at scale. Cookie consent services face unique challenges: read-heavy traffic patterns (every page load queries consent status), strict latency requirements (consent checks block page rendering), regulatory complexity across jurisdictions, and the need to merge anonymous visitor consent with authenticated user profiles. This design covers edge-cached consent delivery, anonymous-to-authenticated identity migration, and a multi-tenant architecture serving thousands of websites.