This protocol is a successor to OStatus (GNU Social), and mostly made by the same people.
From what I remember, Mastodon switched from OStatus to ActivityPub a few releases ago. In the past they had to extend the OStatus protocol for private messages, which meant some clients may not honor the private status of theses posts. ActivityPub has private messages defined properly in the spec.
From what I remember, Mastodon switched from OStatus to ActivityPub a few releases ago. In the past they had to extend the OStatus protocol for private messages, which meant some clients may not honor the private status of theses posts. ActivityPub has private messages defined properly in the spec.
It seems PeerTube (https://github.com/Chocobozzz/PeerTube) will also use ActivityPub.