k61.dev URL Shortener

A serverless URL shortener built on Azure and Cloudflare with sub-10ms edge redirects.

Architecture

flowchart LR
    subgraph Internet
        User([User])
    end
    
    subgraph Cloudflare
        Worker[Cloudflare Worker<br/>k61.dev/*]
    end
    
    subgraph Azure
        SWA[Static Web App<br/>url.k61.dev]
        Functions[Azure Functions<br/>API]
        Storage[(Table Storage<br/>URLs, Users)]
    end
    
    User -->|k61.dev/abc| Worker
    Worker -->|lookup| Storage
    Worker -.->|track click| Functions
    Worker -->|302 redirect| User
    
    User -->|url.k61.dev| SWA
    SWA -->|API calls| Functions
    Functions -->|CRUD| Storage

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Table Schema

erDiagram
    AllowedUsers {
        string PartitionKey "always 'user'"
        string RowKey "email (lowercase)"
        string addedBy "inviter email"
        datetime addedAt
    }
    
    URLs {
        string PartitionKey "first 2 chars of shortcode"
        string RowKey "shortcode (e.g. 2Tn3)"
        string URL "destination URL"
        string Owner "creator email"
        int ClickCount
        datetime CreatedAt
    }
    
    UserURLs {
        string PartitionKey "owner email"
        string RowKey "shortcode"
        string URL "destination URL"
        int ClickCount
        datetime CreatedAt
    }
    
    UserInvites {
        string PartitionKey "inviter email"
        string RowKey "date (YYYY-MM-DD)"
        int InviteCount "invites sent that day"
    }
    
    AllowedUsers ||--o{ URLs : "owns"
    AllowedUsers ||--o{ UserURLs : "owns"
    AllowedUsers ||--o{ UserInvites : "sent"

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Features

• ⚡ Sub-10ms redirects via Cloudflare Workers edge network
• 🔐 Microsoft account auth with allowlist access control
• 📊 Dashboard with click tracking, sorting, pagination
• 🎯 Short 4-char IDs - 14.7M capacity (base62)
• 🆓 Free tier - All services within free limits

Cost

All services run within free tier limits:

Service	Free Limit
Azure Functions	1M executions/month
Azure Table Storage	~$0.045/GB + $0.00036/10K transactions
Azure Static Web Apps	100GB bandwidth/month
Cloudflare Workers	100K requests/day
GitHub Actions	2000 min/month (public repo)

Project Structure

├── workers/      # Cloudflare Worker (redirects)
├── functions/    # Azure Functions (API)
├── web/          # Dashboard app (url.k61.dev)
└── docs/         # Documentation

Development

# Install dependencies
npm install

# Run tests
npm test

# Run linter
npm run lint

Local Development

# Functions (requires Azure Functions Core Tools)
cd functions && npm start

# Web dashboard
cd web && npm run dev

Deployment

All deployments are automatic via GitHub Actions on push to main:

Component	Workflow	Destination
Worker	deploy-worker.yml	Cloudflare Workers
Functions	deploy-functions.yml	Azure Functions
Web	deploy-web.yml	Azure Static Web Apps

Data Model

Azure Table Storage tables:

• URLs - Short ID → destination URL mapping
• UserURLs - Per-user URL index for dashboard
• AllowedUsers - Email allowlist
• UserInvites - Daily invite rate limiting

License

MIT