URL Shortener

Design a public service that creates unique short links and redirects visitors to the original URL. Links expire after a configurable lifetime. Analytics must never slow the redirect path.

• Create a short link from an HTTP(S) URL, with optional expiry.
• Redirect active links; return 404 for unknown links and 410 for expired links.
• Keep a durable mapping from short code to destination.
• Collect click events asynchronously and handle hot links.