Website monitor

I am looking to create a script that runs 24/7 that can catch as soon as possible when stock is loaded onto a website, when a product page is available, and automatically, with the most minimal delay possible, send that information (The Item Loaded and the corresponding link) to to my slackchat webhook channel. I would also love for it to be configurable so that I am able to add in additional sites. I would also love to be able to filter what gets shown on the Slackchat Channel (keywords possibly) as I don't want to get spammed with an obnoxious amount of information from stock loading on the 50+ websites I would like to track. This information is very pertinent to users that resell sneakers and they need the most up-to-date information about a site loading stock on the backend that is available on the front end, or just having an early link to purchase from before everyone else. I have example of such accounts if you are interested, you can respond to this job and you may see what I mean. This information is also super useful when a site is sold out and products restock a few hours or even days/weeks later. Users with this information usually are able to purchase without the public knowing about the restock. I'm not sure on the going rate for this type of project, so I just put a number that I thought was fair for payment. We can talk more about that once details are laid out! Appreciate you taking a look