Spotify — Simple

Problem statement (interviewer prompt)

Design Spotify: music + podcast catalogue, adaptive-bitrate playback, playlists (personal, collaborative, algorithmic — Discover Weekly), recommendation, offline mode, Spotify Connect (control playback on remote devices), and per-stream royalty accounting.

flowchart LR
  U([User])
  CAT[Catalog Service]
  REC([Recommendations])
  PLAY[Playback]
  CDN
  META[(Track metadata)]
  AUD[(Audio files)]
  U --> CAT --> META
  U --> REC
  U --> PLAY --> CDN
  CDN --> AUD

    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 U client;
    class CAT,PLAY service;
    class META,AUD datastore;
    class REC compute;