How to validate and handle URLs which do not exist?

A web application is repository of various cloud documents. The users share the public share link of their respective cloud document in it. Keeping URL pattern check makes sure that any random website URLs are not provided. The only chance of error occurrence remains if there is error in the unique path of the document in URL. Suppose a URL is like https://www.dropbox.com/s/jo0u8xcpr64fw1a/Test%20Document.xlsx?d=0  where ' jo0u8xcpr64fw1a ' is part of unique path. If the path is proper the cloud document will successfully load and if there is error in it, there would be error page with 403 or 404 or other similar pages. By just accepting public share links makes easy to have documents from various cloud storage platform at one place without worries of learning or implementation of their respective APIs. Is there any in-built or third-party method to check header or HTML or something to kno ...