Ad Marketplace System Design

Problem Statement

Design a scalable ad marketplace system that connects publisher websites with multiple ad providers. The system must select an ad for each request, track clicks, enforce daily budgets, and manage advertiser funds.

Given Constraints

• Publishers make synchronous ad requests and expect low-latency responses
• Multiple ad providers bid for each placement
• Each campaign has a daily budget that decreases on clicks and resets daily
• Ads with exhausted budgets must not be served
• System operates globally across regions

Disclaimer: This is a sample solution to help you get started. System design questions are open-ended and have multiple valid approaches.