[jt2190]

There's also a question of what we're really trying to validate, IMHO. All of these regex patterns will tell you that a string looks like a URL, but they won't actually tell you if: There's any web server listening at that particular URL; Whether that server has the resource in that location; If that server is reachable from where you want to fetch it; etc.

[staticassertion]

> All of these regex patterns will tell you that a string looks like a URL,

yeah that's it that's what they're trying to validate

[MPSimmons]

It seems like the answer is almost always yes.