Automagically determining feeds provided for a given URL on the command-line

I'm a big fan of feed formats like RSS/Atom, Microformats2 and JSON feed, and like to use a feed reader as my primary reading source.

One of the great things about things like I mentioned in Make Your RSS Feed Discoverable is that there are built-in ways that you can make them automagically discoverable to tools like feed readers.

However, sometimes you need to manually discover them, for instance if you want to add an RSS/Atom feed to a Slack instance, as Slack doesn't support the discovery means.

Because I end up doing it a fair bit more than expected, I've written a command-line tool, feeds, which allows me to discover all feeds of a given URL, that are marked up with the rel=alternate markup.

For instance:

go build && ./feeds jvt.me
[
  {
    "feedUrl": "https://www.jvt.me/feed.xml",
    "feedType": "application/rss+xml"
  },
  {
    "feedUrl": "https://www.jvt.me/feed.json",
    "feedType": "application/json"
  },
  ...
]

Source code is available on GitLab.

This follows redirects, and handles relative URLs in feeds.