Simple URL shortening.
To set up, rename .env.example to .env and add the necessary values. (Make sure to add a random API_TOKEN, too.) Also add allowed domains to config/allowlist.php.
Creating a shortened URL is done by sending a POST request to https://example.org/shorten, like so:
curl -H "Authorization: Bearer w6xc7RjEC79nFSBKuPZKmn" -d "url=https://some.url/and-so-on" https://example.org/shorten
If the URL in question contains special characters, a query string, etc., it should be run through, e.g., PHP's rawurlencode() first.
If all goes well, the resulting short URL is returned in plain text.
Might later on add rate limiting or an IP-based allowlist, but for now, this is it.