So, I think this hilarious, but link shorteners have to be stable, right? What happens when link shorteners go offline? Is there a way of decoding shortened links without the server?
"So, I think this hilarious, but link shorteners have to be stable, right?"
Yes, a link shortener does need to be stable but luckily they are extremely simple to operate.
You should be able to run a very popular link shortener on a leftover 1U with very low associated bandwidth and power costs. It's not unrealistic for a person, or group, to commit to this indefinitely.
Thinking about it that is absolutely possible, but only for you personally. A site could store your destination as local storage and translate through a service worker (which runs even if the site is offline). Half a page of JS would do it. Not sure if it is useful though?
All link shorteners, even those that use a readable URL, keep the target URL in a database. It's not possible to decode any of them without the service being available.
The novelty here is that the service deliberately makes itself unusable for comedic effect
You could have just an encoding and compression scheme, with no storage, but it wouldn’t be able to shorten the urls by much in most cases.