WebSite-Watcher is a tool for detecting and tracking changes on websites and RSS/Atom feeds. It can compare new page content with previous versions, highlight what has changed, and filter out unwanted parts using keyword filters or more advanced filters such as regular expressions. Users can schedule how often sites are checked, receive alerts or notifications on updates, and archive past versions of monitored pages. There is a free version (for personal/commercial use) that supports basic monitoring and a paid edition with expanded features for business use.