https://jhey.dev/ (@firstname.lastname@example.org) hey! thanks for the kind words.
Two sides to supporting #webmentions:
1. Sending: https://webmention.app/ is excellent, by https://remysharp.com/ (@email@example.com), or you can write your own Webmention sending loop using endpoint discovery libraries, and in that loop you can do other things, like also send each link to the Internet Archive (https://indieweb.org/Internet_Archive#Trigger_an_Archive, what I do on my site) to archive each link as of the time you linked to it.
2. Receiving: https://webmention.io/ (which is what I use) by https://aaronparecki.com/ as recommended by https://mxb.dev/ (@firstname.lastname@example.org), or https://webmention.herokuapp.com/ by https://voxpelli.com/ (@email@example.com) as recommended by https://kryogenix.org/ (@firstname.lastname@example.org). Similarly to sending, you could also write your own Webmention receiving code.
Then the fun part, once you’re receiving webmentions, is figuring out how you want to display them as comments, likes, reposts etc. on your post permalinks. Do you display people’s icons/avatars, at what resolution? Do you display the entirety of comments or do you elide them at 255 characters (or some other limit)? Etc. If(when) you start storing received webmentions in your own site/server’s storage, there’s a bunch more interesting considerations.
That’s a good start. Drop by https://chat.indieweb.org/dev for deep dives into any of the above, and welcome to the Webmentionverse