I mentioned a new service which handles webmentions in a previous post. I decided to replace the glitch I've been using for one which is much leaner. It uses the library which powers webmention.app to handle webmention (and also older technologies like pingback) endpoint discovery and mention dispatch so I took this opportunity to ditch my own discovery code.
I also decided to leave out some features. The earlier glitch would check old posts for new mentions, filter out certain URLs like rendered webmentions from others and so on. This all required a database and meant that posts got checked more than once, which took a long time (beyond the timeout of a glitch run.
The new glitch keeps a list of posts it's already sent mentions for. This means that each post is only scanned once after publication. That avoids the issue of filtering out certain URLs (the rendered webmentions of others for example) since a newly published post won't have any mentions yet. It's also a little more portable. If you like the idea of using a sitemap.txt to drive a record of which posts have been handled, then take a look!
P.S. All the glitches I use to add functionality to my blog can be found here.