Pinterest — Simple

Problem statement (interviewer prompt)

Design Pinterest: users save (pin) images into boards, follow others, and discover via home feed + search + visual-search (Lens) + related pins. Cover the image embedding pipeline (e.g. PinSage) and shopping integrations.

flowchart LR
  U([User])
  P[Pin Service]
  B[Board Service]
  S3[(Object Store)]
  CDN
  IDX[(Visual + Text Index)]
  REC([Recommendations])
  DISC[Discover / Search]
  U -->|create pin| P --> S3 --> CDN
  P --> IDX
  U --> B
  U --> DISC --> REC --> IDX

    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 P,B,DISC service;
    class IDX datastore;
    class REC compute;
    class S3 storage;