It will work. The server will return JSON. The URL http://ipinfo.io/ http://ipinfo.io/ returns HTML if the Accept header indicates that you want HTML, and JSON

It will work. The server will return JSON. The URL http://ipinfo.io/ http://ipinfo.io/ returns HTML if the Accept header indicates that you want HTML, and JSON if there is no header, a wildcard header, or a header that requests JSON. As far as I can see, irm doesn’t add an Accept header, so the command jodrellblank provided will fetch JSON and work correctly.