I've often wanted something that'll alert me when URLs change, and show the resulting diff (e.g. changes to the terms of service or privacy policy of the sites

I've often wanted something that'll alert me when URLs change, and show the resulting diff (e.g. changes to the terms of service or privacy policy of the sites I use, or the page for tracking some FedEx parcel I shipped, or areweatwarwithiran.com). ChangeFeed is designed to basically turn any page into a completely impartial RSS feed.