- Does this use any blacklist to prevent URL shortener looping (i.e. using multiple URL shorteners on top of each other to bypass the checking), or preventing any potentially malicious sites? - Does this have rate limits? URL shorteners get abused quite regularly, so this should be necessary.
I'm planning to blacklist certain problematic hostnames and not let folks add them.
In terms of rate limits, it does have rate limits when it comes to collecting analytics (if you spam click a link >10 times in 10s it still redirects you but it stops recording clicks.
I can't think of how URL looping could bypass checking – could you elaborate?