Is it always safe to remove a trailing slash from a URL?

Question

I'm storing URLs in a database, and I want to be able to know if two URLs are identical.

Generally, a trailing slash at the end doesn't change the response you'd get from a server. (ie. http://www.google.com/ is the same as http://www.google.com)

Can I always blindly remove the trailing slash from any URL, without looking at anything?
Is that safe?

What I mean by "without looking at anything" is that I'd remove the slash from:
http://www.google.com/q?xxx=something&yyy=something/

I know the web server could theoretically return completely different things if it wanted, and I know sometimes going to a URL without the slash will redirect to one with the slash. My only intention here is determining if both URLs are the same.

Is this method safe?

Answer 1

No it is not always safe. A web server could interpret the path part of the URL anyway it likes. You cannot tell what it will do (resolve the URI) without using a GET or HEAD on the URL.

Answer 2

It may be safe in the sense that you'll get the same response with or without a trailing slash (and I can't guarantee that's true), but they can definitely mean different things. Consider a URL that references a directory, or something presented by the site as a directory. Using the URL

http://www.somesite.com/directory/

...makes it clear you're asking for a directory. If you hack off the trailing slash:

http://www.somesite.com/directory

...the site's going to take this as a request for a file called "directory", and get all confused for a moment. It'll likely interpret this as a request for a directory, but the meanings are not the same, and you might not get what you expect.

See this article for more detail.