I think it's worth clarifying that curl DOES NOT validate a given URL more

than what's absolutely necessary:

curl will do its best to use what you pass to it as a URL. It is not trying to
validate it as a syntactically correct URL by any means but is instead
VERY liberal with what it accepts.

docs/curl.1

@@ -75,6 +75,10 @@ protocol you might want. It will then default to HTTP but try other protocols
 based on often-used host name prefixes. For example, for host names starting
 with "ftp." curl will assume you want to speak FTP.
 
+curl will do its best to use what you pass to it as a URL. It is not trying to
+validate it as a syntactically correct URL by any means but is instead
+\fBvery\fP liberal with what it accepts.
+
 Curl will attempt to re-use connections for multiple file transfers, so that
 getting many files from the same server will not do multiple connects /
 handshakes. This improves speed. Of course this is only done on files