System Design: Video Download and Creator Subscription Platform

Question

## Round 1 - System Design

## Problem

Design a backend system that supports two core features for a video streaming platform:

1. **Video Downloads** — authenticated users can download videos for offline playback. Downloads must expire after 30 days and be DRM-protected.
2. **Creator Subscriptions** — users can subscribe to a creator; subscribers get early access to new uploads and ad-free playback.

Cover: API design, data models, storage strategy, and at least one non-trivial scaling concern for each feature.

**Clarifying questions to consider:**
- What is the expected ratio of downloads to streams?
- Should subscription state be strongly consistent or eventually consistent?
- How many creators and subscribers are in scope (order of magnitude)?

## Key Components to Discuss

- Download token issuance, signed URL generation, and expiry enforcement.
- Subscription event fan-out: how to notify millions of subscribers when a creator uploads.
- Storage tiering: hot vs. cold for downloaded content.
- Preventing download link sharing (device binding, token fingerprinting).

## Follow-ups

1. How do you handle a creator with 10 million subscribers uploading a video — what does fan-out look like?
2. Where does the DRM key service live, and how do you protect it from abuse?
3. How do you ensure a user's downloaded library is consistent across two devices?

System Design: Video Download and Creator Subscription Platform

Question Details

Full Details

Topics

More from Netflix