A bot that tracks page changes?

Question

Bots

Is there a project or an open source product, a certain bot to which you show a page for example: https://www.maxgaming.com/en/miscellaneous-ps4/ste... and it polls it after N-th time and if the check differs from the original then the trigger fires. For example, the price has changed, the description on this page has changed, etc. all sorts of different changes and so that triggers work.
Is there something like this on the web? Services such as tracking a cent do not count, just so that the entire page can be tracked, which one do you indicate to the bot or service?

Answer 1

Write your own using Java. And so maybe you will find something here: https://habr.com/en/post/340038/

Answer 2

In Python, you can fit in 10-20 lines of code.