The question is rather straightforward. Even though I said smaller, size doesn't really matter for this - the focus is more on the community aspect rather than it being small. Here's my non-exhaustive list (in no particular order):
- Tildes - This is unsurprising. It's definitely large for a "small" community, but it's managed to preserve it's culture very well, which is rather impressive. It's cozy and has high quality discussion.
- Various Discord servers and IRC channels. This one is harder to pinpoint, to be honest. As far as IRC channels/Discord servers goes, some of the more niche gaming ones are probably some of the nicest environments. IRC-wise, I really haven't managed to find any particularly active ones, outside of the ones for the next list member...
- tilde.town and probably the larger tildeverse. Not affiliated with Tildes, but generally just... a nice place to be. It's rather quiet a lot of the time, but their main IRC channel is, frankly, quite great. When it's active.
- A lot of Mastodon instances, although of course not all. The fediverse is generally a nice place to be, although politics on there is kind of mushy and one sided. Genuine interactions on there, however, are extremely common and sorting by the global timeline is quite nice (most of the time.)
- rateyourmusic is a nice community of those who are passionate about music. It's quite nice overall, though.
There's definitely a lot I've missed out, mainly because I probably don't know about them.
So, what are some of the smaller (or not) communities that you enjoy?