WIP

What is a URL Shortener?

A URL shortener is a simple service, which provides the user a shorter URL in exchange for a long URL. Clicking on either URL—the original long one or the shortened one—ultimately leads the user to the very same webpage. e.g., https://tinyurl.com/ypu6s32v is a shortened URL. (Try clicking it and see where it goes!)

A few popular URL shortening services:

• https://tinyurl.com/
• https://bitly.com/
• https://geniuslink.com/

Why is a URL Shortener needed?

Traditionally, URL shorteners were mostly used to save space in places where text input had character limitations, such as tweets on Twitter (X). Also, sharing a shorter URL with others is easier, looks neat, and is error-free. Moreover, nowadays, a few URL shortening services have advanced features, like incorporating advertisements, tracking click counts, and letting the shortened URL be used for earning commissions.

Designing the URL Shortener

• Get some idea on the scale of the system
  • How many users will use the system daily?
  • How many links will be created daily (writes) vs. visited (reads)?
  • Storage requirements over time (e.g., 5 to 10 years)?
• How to map the Long URL to the shortened URL?
• How will the shortened URL be generated?
• How will the Long-Short URL pair be stored in the database (SQL vs NoSQL)?
• Any time promise regarding the shortened URL? (TTL / Expiration policy, e.g., 5-year, 10-year)
• How to find if a long URL has already been shortened?
• API Design and URL redirection strategy (301 vs 302/307 redirects)
• Other Considerations
  • Caching
  • Rate Limiting
  • Analytics (Click Counts)
  • Custom / Vanity URLs
  • Database Scaling (Replication, Partitioning / Sharding)