Mastodon

Mastodon was initially released in March 2016 as free software to run a self-hosted social media service, with similar features to Twitter.

It slowly grew in popularity, but in 2022 there was a marked increased in interest as people became aware of the acquisition of Twitter by a well-known business man. By the end of 2022 Mastodon was at 1.8 million active users, and a few months later, on 19 March 2023, in past ten million user accounts.

Mastodon is often someone's first experience of the Fediverse.