A crowdfunding platform must coordinate campaign lifecycle, pledge collection, payment authorization, and backer communication — with significantly different flows depending […]

A movie theater booking system must handle concurrent seat selection, pricing rules, and ticket lifecycle from browse to cancellation. This

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

A coupon distribution service needs to handle bulk code generation, targeted delivery, safe redemption, and fraud prevention at scale. This

Airline reservation systems are among the most demanding transactional workloads: thousands of concurrent seat holds, strict inventory partitioning by fare

A library management system handles catalog browsing, checkouts, returns, reservations, and fines. This low level design covers the core schemas

A device fingerprinting service identifies and tracks devices across sessions without relying on cookies or stored identifiers. It is a

An OCR service must handle raw document images, extract structured text, assess confidence, and process jobs asynchronously at scale. Here

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

A QR code generation service must handle encoding, error correction, output formats, and at scale — bulk generation for campaigns,

Autocorrect differs from a spell checker in intent: rather than flagging errors for the user to fix, it silently replaces

In a SaaS product, onboarding a new customer involves far more than creating a database row. The tenant provisioning service

Configuration drift is one of the most common root causes of production incidents. A config diff and change management service

API key rotation is a security control that limits the blast radius of a leaked credential. A well-designed rotation service

Real-Time Location Service A real-time location service ingests high-frequency position updates from mobile clients, indexes them for low-latency spatial queries,