If you're on windows you can use the value of the registry key
'HKEY_CLASSES_ROOT\http\shell\open\command' which gives the default program for handling http=the browser,
using a module such as Win32::TieRegistry,and then use Win32::OLE to pass the url to the browser.
Let'say that the default browser is IE so :

$IE=Win32::OLE->new("InternetExplorer.Application") or die "could not 
+start browser";
$IE->{visible}=1;
$IE->Navigate("$url");
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