How URL Shorteners Work - The Magic Behind Short Links
Why Shorten URLs?
URLs can exceed 100 characters (Amazon product pages, for example). Long URLs clutter messages, eat into social media character limits, and make square patterns larger and more complex. URL shorteners like bit.ly and t.co solve this.
How It Works: Mail Forwarding
Like postal mail forwarding: access bit.ly/abc123, the server looks up the real URL in its database, and sends an HTTP 301 redirect. Your browser automatically navigates to the real destination in about 0.1 seconds.
The Risk: Hidden Destinations
You can't tell where bit.ly/abc123 leads before clicking. Malicious actors hide dangerous links behind short URLs. Add '+' to some short URLs to preview destinations. Security software can auto-check redirect targets. Always verify short URLs from unknown senders.
Dynamic Square Patterns Work the Same Way
Dynamic square patterns use the same redirect principle. A short URL stored in the pattern redirects via server to the real destination. Changing the destination only requires updating the server database - the printed pattern stays the same.
Another weakness that short URLs carry
Besides the problem of the destination being invisible, short URLs have a weakness that is easy to overlook. It is that when the service providing the shortening goes away, all the short URLs using that service lose their function at once. Even if the original long URL is alive, if the shortening mechanism that calls it stops, you cannot reach anywhere. In exchange for convenience, you are entrusting the destination to the survival of an external service. The more you want to use a link for a long time, the more important it is to choose while being conscious of whether the provider will continue stably.
To engage safely with short URLs
Short URLs are a convenient tool, but both the user and the recipient can raise safety with a little care. If you use a mechanism that lets you check the destination in advance before opening a short URL you received, you can ease the anxiety of being sent to an unexpected site. When you make a short URL yourself, choosing a trustworthy provider and adding an explanation that reveals the destination lets the other person open it with peace of mind. Not making shortening alone the purpose, but thinking through to how to compensate for the destination that becomes invisible, is the knack of engaging well with short URLs.
Try Making One
Visit bit.ly and paste any long URL. With an account, you get click statistics. Caution: if the service shuts down (like Google's goo.gl in 2019), all short URLs break. For long-term use (business cards, signs), use your own domain or a reliable service.