Design URL Shortener

URL Shortener System Design:

1. Architecture Components:

   • Load Balancer
   • Application Servers
   • Database (Primary-Secondary)
   • Cache Layer (Redis)
   • Analytics Service

2. Core Services:

interface URLShortener {
  shorten(longUrl: string): string;
  redirect(shortUrl: string): string;
  customize(longUrl: string, customPath: string): string;
}

class URLService implements URLShortener {
  private readonly baseChars: string;
  private readonly redis: Redis;
  private readonly db: Database;

  async shorten(longUrl: string): Promise<string> {
    const id = await this.generateUniqueId();
    const shortPath = this.encode(id);
    await this.store(shortPath, longUrl);
    return this.baseUrl + shortPath;
  }
}

3. Database Schema:

CREATE TABLE urls (
  id BIGSERIAL PRIMARY KEY,
  short_path VARCHAR(10) UNIQUE,
  long_url TEXT NOT NULL,
  user_id UUID,
  created_at TIMESTAMP,
  expires_at TIMESTAMP,
  click_count INTEGER DEFAULT 0
);

4. Key Features:

   • Base62 encoding
   • Collision handling
   • Rate limiting
   • Analytics tracking
   • Cache management

5. Scalability:

   • Horizontal scaling
   • Database sharding
   • CDN integration
   • Cache invalidation

Company Context (Meta):

• Focus on scalability
• Real-time analytics
• Global distribution
• Privacy considerations