Notes
These providers are well-organised, well-funded, long-lasting services that can be reasonably expected to offer a stable experience for new members.
Where the primary language is a Language Other Than English, I have added that as a visual classifier.
I have not included threads.net or bsky.app as they do not fully federate with ActivityPub, which is the general intent of this proof-of-concept. However, some directories or guides may find it appropriate to list these domains.