Friendica

Friendica (formerly Friendika, originally Mistpark) is a free and open-source software[5] distributed social network. It forms one part of the Fediverse, an interconnected and decentralized network of independently operated servers... Friendica users can connect with others via their own Friendica server, but may also fully integrate contacts from other platforms including Diaspora, Pump.io, GNU social, email, Discourse[9] and more recently ActivityPub (including Mastodon, Pleroma and Pixelfed) and Bluesky[10][11] into their 'newsfeed'. https://en.wikipedia.org/wiki/Friendica

built in PHP