Website: https://changedetection.io/
Source Code: https://github.com/dgtlmoon/changedetection.io
ΒΆ Description
"The best and simplest free open source website change detection, website watcher, restock monitor and notification service. Restock Monitor, change detection. Designed for simplicity - Simply monitor which websites had a text change for free. Free Open source web page change detection, Website defacement monitoring, Price change notification."