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
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
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
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
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 A QR code generation service must handle encoding, error correction, output formats, and at scale — bulk generation for campaigns, […] 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
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
7 min read API key rotation is a security control that limits the blast radius of a leaked credential. A well-designed rotation service […] Read article