Google Drive / Dropbox — Simple

Problem statement (interviewer prompt)

Design Google Drive / Dropbox: multi-device file sync, sharing (per-file ACL + link sharing), versioning, full-text search, previews, and live collaborative editing. Cover content-defined chunking, block-level dedup, and conflict resolution.

flowchart LR
  C([Client])
  SYNC[Sync Service]
  CHUNK[Chunker]
  S3[(Block Store)]
  META[(Metadata DB)]
  NOTIFY[Notify / Long-poll]
  C --> SYNC
  SYNC --> CHUNK --> S3
  SYNC --> META
  C2[Client B] --> SYNC
  SYNC --> NOTIFY --> C2

    classDef client fill:#dbeafe,stroke:#1e40af,stroke-width:1px,color:#0f172a;
    classDef edge fill:#cffafe,stroke:#0e7490,stroke-width:1px,color:#0f172a;
    classDef service fill:#fef3c7,stroke:#92400e,stroke-width:1px,color:#0f172a;
    classDef datastore fill:#fee2e2,stroke:#991b1b,stroke-width:1px,color:#0f172a;
    classDef cache fill:#fed7aa,stroke:#9a3412,stroke-width:1px,color:#0f172a;
    classDef queue fill:#ede9fe,stroke:#5b21b6,stroke-width:1px,color:#0f172a;
    classDef compute fill:#d1fae5,stroke:#065f46,stroke-width:1px,color:#0f172a;
    classDef storage fill:#e5e7eb,stroke:#374151,stroke-width:1px,color:#0f172a;
    classDef external fill:#fce7f3,stroke:#9d174d,stroke-width:1px,color:#0f172a;
    classDef obs fill:#f3e8ff,stroke:#6b21a8,stroke-width:1px,color:#0f172a;
    class C,C2 client;
    class SYNC,CHUNK,NOTIFY service;
    class S3,META datastore;