GitHub - dgtlmoon/changedetection.io: Best and simplest tool for website change detection, web page monitoring, and website change alerts. Perfect for tracking content changes, price drops, restock alerts, and website defacement monitoring—all for free or enjoy our SaaS plan!
github.com
Best and simplest tool for website change detection, web page monitoring, and website change alerts. Perfect for tracking content changes, price drops, restock alerts, and website defacement monito...

Just came across this, and thought it was a pretty cool tool to self-host. You can use it to monitor price changes, or new events being added, or to check if that out of stock thing is back in stock.