I am enjoying working in Repl.it -- it's a challenge, some of the kids working on stuff here are soooo far ahead of me in programming, that it can be tough to help them. I'm learning new things all day every day, which is pretty awesome.
It's also been super-motivating for working on my own stuff.
The community is great (join the discord if you haven't already).
Repl does have an HQ in SF. I visited their previous HQ in SF, but they moved to a new one since I visited. Hoping to see it soon.
I believe all the full-time employees are in San Francisco, but there are a few contractors (like Katya and myself) who work remote.