It literally started in 2010, almost six years before Mastodon.

If you’re looking for something that is to Facebook what Bluesky is to pre-Musk Twitter, it doesn’t exist.

Otherwise, “the Facebook ones” are:

• Friendica (intended to be a Facebook alternative from the very beginning, designed to federate with everything that moves)
• Hubzilla (fork of (a fork of?) Friendica by Friendica’s own creator, currently the most powerful piece of server software in the whole Fediverse, basically a federated Swiss army knife that can do Facebook as well)
• the nameless thing in the streams repository (not in this graph, fork of a fork of a fork of a fork… of Hubzilla by Friendica’s and Hubzilla’s creator, less feature-laden than Hubzilla, but more modern and evolving at a rapid pace, the most advanced piece of server software in the whole Fediverse, but instances are hard to find)