Day 2: Marketplace Platform - AI System Design in Seconds

Building a two-sided marketplace is one of the most interesting system design challenges you'll encounter. You're not just designing a single application, you're orchestrating interactions between two user types, managing inventory in real-time, and ensuring trust through reviews and ratings. This Day 2 challenge explores the architecture behind platforms like Etsy, revealing the complexity hidden beneath a simple "buy" button. Architecture Overview A marketplace platform requires several core components working in concert. The user service manages both buyers and sellers, handling authentication and profile management for each group. The product catalog stores listings with inventory counts, search indexes, and filtering capabilities. The order management system processes purchases, tracks status, and coordinates between buyer and seller. Payment processing handles transactions securely, while a notification service keeps users informed of order updates, new messages, and reviews. The