Log Aggregation Pipeline: Low-Level Design A log aggregation pipeline collects structured logs from thousands of services, parses and enriches them, […]

Live Chat System: Low-Level Design A live chat system must maintain persistent WebSocket connections, fan out messages in milliseconds to

Threaded Comment System: Low-Level Design Threaded comment systems power discussion on news sites, forums, Reddit-style boards, and product pages. The

Knowledge Base System Low-Level Design A knowledge base must do three things well: let authors maintain accurate articles without losing

Image Moderation Pipeline Low-Level Design User-generated image content requires automated screening at scale. A purely manual review operation collapses under

Tax Calculation Engine Low-Level Design Tax calculation sits at the intersection of accuracy and auditability: a one-cent rounding error multiplied

Device Management System Low-Level Design A device management system answers three security questions: what devices have accessed an account, how

Audit Log Export System Low-Level Design Compliance teams and security analysts regularly need bulk exports of audit log data for

Bulk Data Import System Low-Level Design Bulk import is one of those features that looks straightforward until a user uploads

Data Retention Policy System Low-Level Design Every production database accumulates data that must eventually be purged, archived, or anonymized —

Push Notification System Low-Level Design A push notification system must reliably deliver time-sensitive messages to millions of devices across Android

Two-Factor Authentication Backup Codes: Low-Level Design When a user loses access to their TOTP authenticator app, backup codes are the