ik.si doesn't require any type of registration to use the service.
You can use the service to shorten any type of links. No limitation to warez, porn. We do have a page where a person can submit various scam and virus websites.
Input the URL that you want to shrink, a custom tag if you want, and that is it, the short link is generated for you. No hassle.
We have an API for you to use with your applications, easy to use. Just visit this page and get started. Again, no registration.