⏱ 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

⏱ 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 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

⏱ 8 min read A coupon distribution service needs to handle bulk code generation, targeted delivery, safe redemption, and fraud prevention at scale. This Read article

⏱ 7 min read Airline reservation systems are among the most demanding transactional workloads: thousands of concurrent seat holds, strict inventory partitioning by fare Read article

⏱ 6 min read A device fingerprinting service identifies and tracks devices across sessions without relying on cookies or stored identifiers. It is a Read article

⏱ 6 min read An OCR service must handle raw document images, extract structured text, assess confidence, and process jobs asynchronously at scale. Here Read article

⏱ 6 min read A barcode scanner service must handle multiple symbologies, noisy real-world images, fast mobile frame processing, and integration with product catalogs. Read article

⏱ 6 min read A QR code generation service must handle encoding, error correction, output formats, and at scale — bulk generation for campaigns, Read article

⏱ 5 min read Autocorrect differs from a spell checker in intent: rather than flagging errors for the user to fix, it silently replaces Read article

⏱ 8 min read In a SaaS product, onboarding a new customer involves far more than creating a database row. The tenant provisioning service Read article