Congrats! But, reading the source, I cannot but wonder: would this not work much easier with a simple .htaccess or nginx redirect-map.conf.
It seems to do the exact same, but with an additional layer of complexity and slowness on top (php).
Not meant as criticism on launching (again: congrats!) just my curiousity after building and hosting several link shorteners myself.
Some PHP pseudocode to explain the idea here https://gist.github.com/berkes/aa4ada274c0d44dd6747cca3beed327e (yes, I haven't written PHP in over 14 years, lol).
Idea is to decode/encode the URL using e.g. base64 or base85 (legibility). I've also tried compression algos, but representing that in url is hard.
It won't shorten much. Most usefull if you can remove the domain from long urls when you only redirect to e.g. your own blog.
Bitcoin Maston Instance