Author name: techinterview.org

⏱ 9 min read Introduction Electronic Health Record systems store and exchange patient health data across providers, payers, and patients. Design must prioritize data […] Read article

⏱ 8 min read Airport management systems orchestrate hundreds of daily flight operations including gate assignment, ground handling, baggage routing, and passenger information display. Read article

⏱ 8 min read ATM networks process card transactions across millions of terminals through authorization switches. The design must be highly available, idempotent, and Read article

⏱ 9 min read Introduction KYC (Know Your Customer) requires verifying user identity using government-issued documents. It is a regulatory requirement for fintech companies, Read article

⏱ 10 min read Introduction Collaborative editors in the style of Google Docs allow multiple users to edit the same document simultaneously with real-time Read article

⏱ 8 min read Introduction Live streaming requires low-latency ingest, real-time transcoding to multiple bitrates, and global CDN distribution to millions of concurrent viewers. Read article

⏱ 9 min read An ad serving system delivers targeted advertisements to users in real time, managing the full lifecycle from auction to billing. Read article

⏱ 8 min read Drone delivery is one of the more mechanically complex LLD problems: you have a physical object moving through three-dimensional space, Read article

⏱ 11 min read Real-time traffic routing is one of the canonical systems design problems — and also one of the most algorithm-heavy LLD Read article

⏱ 10 min read Autonomous vehicle fleet management sits at the intersection of real-time embedded systems, cloud infrastructure, and safety-critical engineering. This LLD covers Read article

⏱ 8 min read A sports betting platform is one of the harder LLD problems because it combines real-time odds management, strict financial controls, Read article

⏱ 6 min read A customer support ticket system coordinates incoming requests across channels, routes them to the right agents, enforces SLAs, and provides Read article

⏱ 8 min read A crowdfunding platform must coordinate campaign lifecycle, pledge collection, payment authorization, and backer communication — with significantly different flows depending Read article

⏱ 8 min read A movie theater booking system must handle concurrent seat selection, pricing rules, and ticket lifecycle from browse to cancellation. This Read article

⏱ 7 min read An e-learning platform must handle course catalogues, student enrollment, video delivery, quizzes, and certificates at scale. This low level design Read article