NextScripts SNAP - A WordPress plugin that can publish posts to to social networks as nicely formatted messages. Works with profiles, business pages, community pages, groups, etc.

Bridgy - Bridgy pulls comments, likes, and reshares on social networks back to your web site. You can also use it to post to social networks - or comment, like, reshare, or even RSVP - from your own web site. https://brid.gy/

Friendica - Decentralisation - Privacy - Interoperability

Scuttlebot - A peer-to-peer log store

Scuttlebutt - A decent(ralised) secure gossip platform.

Webmention.io - Webmention.io is a hosted service created to easily receive webmentions on any web page.