Feed Canary
Feed Canary watches your RSS feed and emails you if it’s missing or invalid.
Hacker News thread linking to an article that covers lots of RSS reading options that are available in late 2025. The article is interesting enough, but what's even more interesting is how many HN comments are "oh they didn't list this thing I use" or, just as often, "well I use this RSS reader I wrote myself".
So, yeah, everyone on HN has written an RSS reader it seems.