Design an online marketplace for buying and selling
Company: eBay
Role: Software Engineer
Category: System Design
Difficulty: hard
Interview Round: Onsite
Design a backend for an online marketplace where users list items for sale and others purchase them. Cover core APIs, data model, search and filtering, image handling, payments/escrow, inventory and availability, notifications, fraud/abuse prevention, rate limiting, and observability. Discuss scaling strategies (partitioning, indexing, caching, CDN), consistency across orders and listings, and a multi-region deployment plan with disaster recovery.
Quick Answer: This question evaluates competency in large-scale system design, covering distributed systems, data modeling, scalability, consistency, security, payments and escrow, media handling, and operational concerns for a two-sided online marketplace.