https://lemmit.online/ is trying to archive Reddit, as are the people at r/DataHoarders (the link https://libreddit.projectsegfau.lt/r/DataHoarder/comments/146msr8/is_there_a_complete_backup_of_reddit/ will not give traffic to Reddit). https://the-eye.eu/redarcs/ is an existing Reddit backup, though I don’t know how complete it is.

Thank you for the clarification! I don’t use Mastodon because I’ve never really been interested in Twitter, so I was very unaware of that.

what makes Mastodon style federation even better than that is that you can move your account from one server to another in a way you really can’t for email.

Not sure how that works. With emails, if I move from [email protected] to [email protected] I lose my old emails and people trying to contact me there, but I can just start over. If I remember peoples’ emails I can also tell them I moved to protonmail and to talk to me there. With federation, if I move servers I lose my comment, post, and upvoted history; people messaging me; and my subscribed communities; but I can just start over. If I remember people’s usernames and subscribed communities I can tell the people I moved and to talk to me there, and re-subscribe on the new account. Unlike with email I can still see my old account’s comments and posts, but otherwise I’m not sure how moving accounts in the Fediverse is different from changing emails.