If you want to move with your feet, Mastodon [1] is rapidly growing in popularity, and it's completely open source [2].
Disclaimer: I used to run a mastodon instance, now I run a pleroma [3] instance to save on memory/cpu usage. Feel free to ask me any questions.
[1]: https://joinmastodon.org/
Think about the money and it's not so strange. Everyone has a price.
I'm not saying it's right, but it's not a mystery. The got big off the backs of others and they've been screwing them over ever since. People building stuff on top of Twitter are crazy. They've been developer hostile for years and years now.
Mastodon is really nice, but it's fairly intensive. Precompiling the rails/webpack assets in particular made my tiny VPS choke, even with 4GB of memory I believe. It also requires Sidekiq and other services [1].
Pleroma is newer and written in Elixir/Phoenix purely as an API. It only has itself as a dependency, and it's lean enough to run on a Raspberry Pi. It offers two frontends, pleroma-fe and mastofe, the latter is a port of Mastodon's UX.
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Features wise, Pleroma doesn't really have a lot beyond the basic functionality of subscribing to people, posting, etc. There aren't real moderation tools (yet), since it's mostly a weekend project for the core devs. Blocking instances requires an IP block still, I think.
Mastodon wins features-wise, hands down. But some things aren't really easy to reconfigure- since the frontend is baked in, changing things like the post character limit (500 chars) is tedious. In pleroma it's a simple config file change.
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I like Pleroma personally but it's not for everyone (yet). I plan on contributing more soon to help change that.
I also was only running single user instances so I can't really discuss scaling. @technowix@niu.moe [2] would be better to ask about that, considering their instance has ~3k users [3].
[1]: https://github.com/tootsuite/documentation/blob/master/Runni...
Mastodon and Pleroma are both part of the Fediverse [2]. They work with any software that works with OStatus and the newer ActivityPub. This includes things like GNUSocial, etc.
Mastodon doesn't explain any of this well, or at all, to my dismay. (As far as I'm aware, on the joinmastodon page).
https://github.com/tootsuite/documentation/blob/master/Runni...
Ta for bringing this to my attention. I'm ploughing through the docs ...