I don’t know if Diaspora was the first of the alternatives to come along, but it was certainly the first I was aware of. It got a lot of attention for the college students who first put it together (and remember that Facebook was originally created by a college student, Mark Zuckerberg). The four students, Ilya Zhitomirskiy, Dan Grippi, Max Salzberg, and Raphael Sofaer, were inspired by a speech Eben Moglen gave to the Internet society’s New York Chapter, where he described centralized social networks as “Spying for free”. The students chose the name Diaspora, which is a Greek word that means a “scattered or dispersed population” to reflect the idea that instead of a centralized platform, Diaspora would consist of independent nodes, called pods, each running a copy of the free software which is open source and licensed under the GNU-AGPL-3.0 license. https://www.zwilnik.com/?page_id=1032

Links:

https://diasporafoundation.org/

https://en.wikipedia.org/wiki/GNU_General_Public_License

https://softwarefreedom.org/

https://web.archive.org/web/20111002003516/http://blog.diasporafoundation.org/2011/09/21/diaspora-means-a-brighter-future-for-all-of-us.html

https://podupti.me/

https://pod.haxxors.com/i/394c80269066

https://www.zwilnik.com/?page_id=1032