In this case study, we examine the design of a scalable system for managing and counting “likes” on a social media platform. Such a system must handle high volumes of user interactions efficiently, ensuring reliability, low latency, and scalability to…

1. Overview A scalable notification service is a critical backend component for modern applications, responsible for delivering timely, personalized messages to users across multiple channels (push notifications, email, SMS, in-app, WhatsApp, etc.). This system powers user engagement in products like…

1. Overview A distributed job scheduler is a system that reliably executes tasks (jobs) at specified times or intervals across a cluster of machines. It powers background processing in virtually every large-scale application: cron jobs, ETL pipelines, report generation, cache…

1. Overview A distributed rate limiter is a critical infrastructure component that enforces per-entity request quotas across a fleet of stateless application servers (e.g., microservices behind a load balancer). In a single-node system, rate limiting is trivial (in-memory counter), but…

1. Overview This case study presents a comprehensive design for a fully distributed, highly available, and linearly scalable key-value store, directly modeled after Amazon’s Dynamo technology (the foundational system behind DynamoDB, Riak, Cassandra, and Voldemort). The core philosophy is radical…

1. Overview This case study outlines a scalable, distributed web crawler architecture capable of processing billions of pages daily. It incorporates fault tolerance, politeness policies, and deduplication. The implementation leverages .NET 8 for high performance, with components for orchestration, fetching,…

1. Functional Requirements 2. Non-Functional Requirements 3. Estimation (Back-of-the-envelope) 4. High-Level Architecture Key Insight: 99%+ of traffic is GET /:shortCode → 301 redirect → Optimize the redirect path aggressively. 5. Core Design Decisions 5.1 Short Code Generation Strategy Option Chosen:…