Tool / Website to monitor a website for changes?

Does anyone know of a website, or preferably an open source solution, that monitor a website and send me a notification (email) when it changes?

This is for a single purpose (to monitor the easyJet schedule release page), so I can get notified within minutes of the new flights getting released. Easyjet do send out an email when it happens, but it’s normally 12-24 hours later, so the really cheap flights are gone. Really cheap being relative nowadays!.

I’ve found a few sites that offer this service, but for anything faster than a check every 24hrs they charge. I’ve also found a couple of opensource solutions, like this one, GitHub - dgtlmoon/ - The best and simplest self-hosted free open source website change detection tracking, monitoring and notification service. An alternative to Visualping, Watchtower etc. Designed for simplicity - the main goal is to simply monitor which websites had a text change for free. Free Open source web page change detection but while I’m comfortable with opensource stuff, I get lost with the whole github thing.