URL Shortener Service

A robust URL shortener service built with Golang that converts long URLs into short, easy-to-share links. The service includes rate limiting, usage statistics tracking, and a RESTful API.

Features

• URL Shortening: Convert long URLs to short codes using base62 encoding
• Rate Limiting: Prevents API abuse with configurable request limits
• Usage Statistics: Track clicks, referrers, and other metrics for each shortened URL
• RESTful API: Complete API for managing shortened URLs
• Persistence: Data stored in a database for reliability

API Endpoints

Method	Endpoint	Description
GET	/urls	Retrieve all shortened URLs
POST	/urls	Create a new shortened URL
GET	/urls/:shortCode	Redirect to the original URL
PUT	/urls/:shortCode	Update an existing shortened URL
DELETE	/urls/:shortCode	Delete a shortened URL
GET	/urls/:shortCode/stats	Get usage statistics for a specific URL

How It Works

URL Shortening Process

The service uses base62 encoding (a-z, A-Z, 0-9) to generate short codes for URLs. This approach allows for:

• Creating shorter URLs than with hexadecimal encoding
• Generating up to 62^n unique URLs where n is the length of the short code
• Avoiding confusing characters like 'O' and '0'

Rate Limiting

To prevent abuse, the service implements rate limiting on API requests:

• Configurable limits by IP address or API key
• Sliding window algorithm for fair usage calculation
• Clear rate limit headers in API responses

Usage Statistics

For each shortened URL, the service tracks:

• Total clicks
• Unique visitors
• Referrer sources
• Geographic data
• Browser/device information
• Timestamp of visits

API Usage Examples

Create a Shortened URL

curl -X POST http://localhost:8080/urls \
  -H "Content-Type: application/json" \
  -d '{"original_url": "https://example.com/very/long/url/that/needs/shortening"}'

Response:

{
  "original_url": "https://example.com/very/long/url/that/needs/shortening",
  "short_code": "aBc123",
  "short_url": "http://localhost:8080/urls/aBc123",
  "created_at": "2023-05-20T15:30:45Z"
}

Get Statistics for a URL

curl -X GET http://localhost:8080/urls/aBc123/stats

Response:

{
  "short_code": "aBc123",
  "original_url": "https://example.com/very/long/url/that/needs/shortening",
  "created_at": "2023-05-20T15:30:45Z",
  "stats": {
    "total_clicks": 42,
    "unique_visitors": 24,
    "referrers": {
      "google.com": 15,
      "twitter.com": 12,
      "direct": 15
    },
    "daily_clicks": [
      {"date": "2023-05-20", "clicks": 10},
      {"date": "2023-05-21", "clicks": 32}
    ]
  }
}

Installation

Prerequisites

• Go 1.16 or higher
• Database (PostgreSQL, MySQL, or Redis)
• Docker (optional)

Local Setup

1. Clone the repository:

   git clone https://github.com/yourusername/url-shortener.git
   cd url-shortener
   

2. Install dependencies:

   go mod download
   

3. Configure the application (edit config.yaml or use environment variables)

4. Run the application:

   go run main.go
   

Docker Setup

docker build -t url-shortener .
docker run -p 8080:8080 url-shortener

Configuration

The service can be configured via environment variables or a config file:

server:
  port: 8080
  host: "localhost"

database:
  type: "postgres"
  connection: "postgresql://user:password@localhost:5432/urlshortener"

ratelimit:
  requests: 100
  period: "1h"

shortcode:
  length: 6

Implementation Details

Base62 Encoding

The URL shortening service uses base62 encoding to generate compact short codes. The implementation converts a numeric ID to a character string using the following character set:

0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz

Here's a simplified example of the encoding function:

func base62Encode(number uint64) string {
    const base = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
    length := uint64(len(base))
    var encodedBuilder strings.Builder
    
    for number > 0 {
        encodedBuilder.WriteByte(base[number%length])
        number = number / length
    }
    
    encoded := encodedBuilder.String()
    return reverse(encoded)
}

License

This project is licensed under the MIT License - see the LICENSE file for details.