Ask HN: How do you keep track of your concurrent website diffs?

I was wondering how people working in a particular domain monitor and keep track of their concurrent websites. Here are the features I was thinking about: * Regular crawl a selection of base URLs when something has changed * Make screenshots of all pages * Keep a git-diff of each changes * Web interface to browse all the changes * Self-hosted Any input would be greatly appreciated. [EDIT] - Formatting