Thank you.

To check the url is one thing, but i want to know if an url was added before.

then i have to parse the url with all the different possibilities:

https://
http://
www.domain
domain
domain.xxx (we take it, but admin should know it that there is the same domain but with another ending.
and
www.domain.com/ and www.domain.com
and maybe www.domain.com/index.php, html, home.php and so on.

I would like to know if there is anything, maybe a perl or php bibliothek, an article or something about this problem.

I see some points, but still not a solution that fits to everything.

What is the query to test the url?
Should i just show everything that is more or less equal and ask the user, if he still wants to send the new url?
Like: Hey, we have

....
....
....

Do you still want to add your url? Be careful not to add twice, because then we ... send a rocket to your home town ...


What i do with lala.wordpress.com or websitebuilder.com/annabelle? Do i need lists with such domains?