I forgot about one, I use it everyday.
Freetube - Open source YouTube player which uses youtube-dl for playing videos, also capable of subscriptions with no google account needed and with routing over tor network. It even uses invidio.us API, which is privacy oriented YouTube frontend.
And I forgot another one! 😀
Fosstodon is an English speaking Mastodon instance that is open to anyone who is interested in technology; particularly free & open source software.