#python and #ubuntu are heavily filled on freenode with over a thousand users though? As well as #debian and #go-nuts (for Go) I think IRC is plenty popular, now if the vast majority idle is another story, people are from all around the globe.

Like #node.js, they have 1000-2000 users connected with probably the same level of engagement, so probably 98% idle which means it's effectively a chat room for about 15 people.

And each person needs to care enough about IRC (e.g. run a VPS) to receive pings or messages while they are away and to see the message history when they return.

Maybe IRC is "plenty popular" which apparently means popular enough to find someone willing to shoot the shit with you if you're in one of its largest channels. But that's a far cry from "IRC is everywhere".

I use IRC every day. I'm just not left scratching my head when I find out that yet another ecosystem chose Slack/Discord over IRC. It blew me away when I saw how active Elm's Slack was while #elm is dead. But that's pretty much how it is with every community I'm part of with a Slack channel.

Sometimes people here suggest "maybe IRC is just for developers", but you can't even format a code block on IRC. :)

Over a thousand users; I wouldn't consider that popular. There are 6 times more people dying every hour than total number of users in those channels. And many of those probably overlap.

“Large” means #rust on moznet, which normally has around a thousand people in it, and has scores of regulars actively chatting.

From the reply to my sibling post and yours, I stand corrected. It seems IRC is big with older languages like C and related (as in, a similar domain) ones like Rust[1]. JavaScript and new, web related languages like Elm are more likely to use Slack.

[1] I'm curious as to whether that IRC channel is the only "blessed" Rust chat out there. The problem with other languages is that the community makes a Slack for them even though there's an IRC channel for them already and most new users start only going to the Slack.

With Rust, I've only heard of some people making Slacks. I don't use Slack, but at least one person mentioned on IRC that the Rust slack they were in was pretty much dead, so I'm not aware of this happening to Rust yet. We'll see as time goes on. There are something like 50 #rust- channels on Mozilla's IRC and ##rust on Freenode, though.

I've also heard of quite a few very active JavaScript Freenode channels, though Slack does have a lot of inroads there depending on which particular segment of the community you're into.

There are a bunch of substantially less trafficked, though definitely regularly active, channels for Rust: #rust-offtopic, #rust-internals, #rust-beginners (this one is recommended in the official documentation and is well-traficked), #rust-osdev, several others too.