Design a marketplace price tracking service
Company: Meta
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Onsite
Design a large-scale product price tracking service similar to an e-commerce price monitor. Users can submit product links from a major online marketplace, view historical price changes, and receive alerts when a product drops below a target price.
Your design should address:
- Product URL ingestion and canonicalization
- Periodic price collection for millions of tracked products
- Historical price storage and visualization
- User-defined alert thresholds and notifications
- Deduplication when many users track the same product
- Freshness, scalability, reliability, and operational constraints
Quick Answer: This question evaluates a candidate's ability to design scalable, reliable ingestion and processing pipelines, time-series price storage and querying, deduplication across users, and notification/alert mechanisms for a large-scale price-tracking service.