LinkedIn — Simple

Problem statement (interviewer prompt)

Design LinkedIn: professional profiles, an asymmetric connection graph (1st/2nd/3rd degree), feed of posts + articles, people + job search, recommendations (PYMK, jobs you may like), and messaging. Handle 1B users with strong privacy controls.

flowchart LR
  U([User])
  P[Profile Service]
  G[Connection Graph]
  F[Feed]
  S[People Search]
  J[Jobs Service]
  MSG[Messaging]
  U --> P
  U --> G
  U --> F
  U --> S
  U --> J
  U --> MSG

    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,G,F,S,J,MSG service;