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Wildebeest - A cloudflare based Fediverse server
(github.com)
A community dedicated to fediverse news and discussion.
Fediverse is a portmanteau of "federation" and "universe".
Getting started on Fediverse;
Because I'm petty
I also don't know those three companies off the top of my head, and while I definitely believe you, I can't imagine they are anywhere near as big as Cloudflare. If you're talking about cloud service providers, I'd also consider running an instance that ignores say, AWS instances, but I think that's a bit different since they don't specifically provide "activitypub" services afaik. With Cloudflare, it's much more explicit