There are browser extensions like Reddit Check or What Hacker News Says which will show Reddit and/or HN comments on any website you visit. So it's very similar in functionality. Sometimes it can be useful. https://chrome.google.com/webstore/detail/reddit-check/mllceaiaedaingchlgolnfiibippgkmj. - Source: Hacker News / 12 months ago

I know you're advertising a tool you made, but I'd be remiss if I didn't mention another cool Chrome extension: Reddit Check. Source: over 1 year ago

Reddit Check - Doesn't find as many threads as the above but seems to work on every website. Make sure to disable exact match and save in options for the best results. Source: almost 2 years ago

Https://visualping.io does a nice similar job and is free for moderate personal use. - Source: Hacker News / 10 months ago

Could try visualping.io but it's not gonna be as convenient as coursicle. Source: almost 1 year ago

You can also monitor up to five webpages for free with VisualPing. Source: about 1 year ago

As a belt and braces approach you could try using something like visualping.io (others are available) to monitor the URL https://recruitment.raf.mod.uk/apply/applying-for?c=15&r=293&type=regular and check when the wording "THIS ROLE IS CURRENTLY CLOSED FOR NEW APPLICATIONS. PLEASE REGISTER YOUR INTEREST AND WE WILL BE IN TOUCH WHEN IT REOPENS." disappears, and it will send you an email when it detects a change. Source: about 1 year ago

Also I was using https://visualping.io/ to track the change. Like you can track the change on the button change for that particular page ( like the button being now back in stock instead of grayed out). Source: over 1 year ago