@ajroach42 GNU Social was written by leftist free software advocates from https://social.umeahackerspace.se/ .
Also, the many quitter-sites like quitter.se, quitter.no and quitter.es, and sites like gnusocial.de or gnusocial.no definitely aren't "free speech maximalists".

Pleroma is not related to gamergate (or political in any way), it's just a lightweight OStatus server written in Elixir that implements the GS and Mastodon APIs.

There's also Friendica http://friendi.ca/ which implements multiple protocols (OStatus and Diaspora, AFAIK).

https://en.wikipedia.org/wiki/Fediverse also lists Hubzilla, which I have only heard briefly about.