File Storage & Sync (Dropbox)

Difficulty: Easy

What It Tests

Blob storage, chunked uploads, client sync protocol, conflict resolution.

Topics Covered

• Blob / Object Storage
• CDN (Content Delivery Network)
• API Design
• Database Design: SQL vs NoSQL
• Networking Essentials

Hello Interview Breakdown

Read the full Hello Interview breakdown →

Approach Hints

• Split files into fixed-size chunks and upload each to S3, store a chunk manifest in a relational DB
• Use delta sync to only upload changed chunks
• Detect conflicts using vector clocks or last-write-wins
• Serve downloads via CDN-backed pre-signed S3 URLs for low latency

Video Walkthroughs

• ByteByteGo: Google Drive System Design | Dropbox System Design | File Sharing Service System Design →
• System Design: Dropbox (5+ Approaches) →