Here, stackoverflow, Software Engineering StackExchange, also there are some Facebook and LinkedIn groups surrounding programming topics specifically. There were also some Google Groups but I don't think they're as active anymore.
I believe there is a site called dev.to , but i like Hashnode community more :)
As far as I know, there are only two big communities, which are 100% directed at programmers. My personal favorite is Hashnode.com. Other than that, there is also dev.to, though that one feels more like a blog (medium?) for devs than a community.
There are a lot of smaller ones, though I have rather bad experiences with them and they do not seem to be as active as the above mentioned ones, like DreamInCode.net.
Other than that, many companies have their own dev communities, like Mozilla, Microsoft, Valve, etc.
If you are okay with social media sites, which have dev groups, then you might want to take a look at Reddit, Facebook, Twitter, etc.
J03
Just another bit in the byte
hashnode.com is pretty decent.