High-Performance URL Shortener

A scalable, serverless API for shortening URLs, built with Go on Cloud Run, Firestore for storage, and Redis (Memorystore) for caching. Handles 10K+ RPS with <100ms latency.

Architecture

sequenceDiagram
    participant C as Client
    participant CR as Cloud Run (Go App)
    participant R as Redis (Cache)
    participant F as Firestore (DB)

    Note over C, F: Shorten Flow
    C->>+CR: POST /shorten { "url": "https://example.com" }
    CR->>+F: Store {short_code, original_url, created_at}
    F-->>-CR: Ack
    CR-->>-C: { "short_url": "https://app.run.app/abc123" }

    Note over C, F: Redirect Flow (with Cache)
    C->>+CR: GET /abc123
    CR->>+R: GET abc123 (cache check)
    alt Cache Hit
        R-->>-CR: "https://example.com"
        CR-->>-C: 302 Redirect
    else Cache Miss
        R-->>-CR: Miss
        CR->>+F: Get doc by short_code
        F-->>-CR: {original_url}
        CR->>+R: SET abc123 "https://example.com" (TTL 1h)
        CR-->>-C: 302 Redirect
    end

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