Q. I’m editing a bibliography that has many URLs that end in a slash. Should these be deleted?
A. A URL copied out of a browser’s address bar and pasted into a document will often include a trailing slash. For example, if you call up the home page of the New York Times and copy its address from Chrome, Edge, or Firefox, you’ll get this: https://www.nytimes.com/. That slash will appear in the pasted result even if it isn’t there in the address bar.
You don’t need to keep the slash at the end of the URL for the Times; trailing slashes can generally be omitted from domain-level URLs like that one. But deleting a bunch of slashes from a long reference list would risk introducing errors—and any URL that goes deeper than a home page would need to be double-checked without a final slash to make sure it still works that way.
So the safest approach is to leave them alone (assuming they work).
By the same token, there’s usually no need to add a slash to a URL that doesn’t already end in one. Especially if the URL points to a specific file, you’re likely to break the link if you modify it in any way.