Design an Instagram-like Media Feed
Company: Meta
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Onsite
Design an Instagram-like photo and video sharing service.
Core requirements:
- Users can create accounts, follow and unfollow other users, and view profiles.
- Users can upload photos and short videos.
- Users can view a personalized home feed containing recent or ranked posts from accounts they follow.
- Users can like, comment on, and delete posts.
- Media should be served with low latency through a CDN.
- The system should be highly available and eventually consistent where appropriate.
Discuss APIs, data models, storage, media upload and processing, feed generation, caching, scaling, reliability, and monitoring.
Deep-dive follow-up: The upload flow uses object-storage pre-signed URLs so clients can upload media directly. How can the system prevent or mitigate malicious uploads? In particular, discuss why size limits and server-side validation help, what they do not solve, and what additional controls should be used.
Quick Answer: This question evaluates a candidate's system design skills, including distributed systems architecture, API and data model design, large-scale media storage and CDN delivery, feed generation, caching, and security/abuse mitigation for uploads.