China has WeChat and QQ (though WeChat is way more popular). Both are basically mini OSes at this point, with apps and other third party functionality able to be built on top of them. I'm not Chinese, but use both of these apps to stay in touch with Chinese friends and family.

Yep, WhatsApp for normal people in Europe; Telegram or Signal for those suspicious of Facebook.

I kind of miss XMPP, which seemed like the answer at one point. As it is, I need about six messaging apps (WhatsApp, Facebook Messenger, Signal, Telegram, a Matrix client, Slack, and I'm probably forgetting one) plus SMS/iMessage to keep in touch with everyone.

Despite what HN seems to think, XMPP is still alive and evolving.

https://snikket.org/ is worth checking out as a (self-)hosted personal chat system.

So true, XMPP is fantastic. I also use it for SMS and signal (I wrote some simple bridges for Prosody). We use it for work too. It's great to have it on all my devices. Group chats (MUC) also work well. The modularity is where it really shines. Conversations on Android keeps a long running TCP session open, it works better than push based solutions and is just as light on battery somehow.

I mean, it still exists, but approximately no-one uses it. There was a time when you could talk to people on Google and Facebook's chat systems with it.

In the U.S and Canada the dominant chat app is facebook messenger.

WhatsApp seems to dominate in Europe and South America.

I’m surprised. The younger generations (including my own, and I’m closer to 40 than 20…) seem to have abandoned the main Facebook product en masse in favor of first Instagram and then others. Are people still using FB Messenger stand-alone even if not using Facebook itself?

I still use FB Messenger to keep in contact with a group of friends. I would love to use something else, but we were never able to agree on another platform to switch too... I barely use Facebook, don't have the app installed, and would probably stop using it completely if that group chat moved elsewhere.

I have FB Messenger, WhatsApp, Signal, Telegram and Discord on my phone...

WhatsApp has 2 billion MAU. It dominates everywhere.

Everywhere except for the US and China.

In Asia, it's a mixture of whatsapp, LINE (Japan/Thailand/Korea), Alichat, Wechat. Australia is a mixture of FB messenger and Whatsapp for families. Kids use different services depending on how old, snapchat, tiktok, instagram, discord (very much so for kids in the "fortnite years").

LINE and Ali/We chat are now more like platforms, for example, LINE has a wallet called LINE Pay that you can use in retail stores that grew out of selling virtual stickers for their chat client. They integrate to transit services and other things too.

LINE, despite being a Korean company (AFAIK) doesn't seem to have gotten traction in its home country as it has in Japan and elsewhere in Asia.

Kakao utterly dominates the market for messaging there (as it does amongst the international Korean diaspora). Even government services use it.

Also Viber that used to be the main contender of WhatsApp in Western Europe up until a couple of years ago. I believe it's still beating WhatsApp on market share in a couple of markets like Israel iirc.

WhatsApp dominates most of the world. Yes in Asia there are a few heavily used apps. Line. WeChat etc.

Even still most in Asia also use WhatsApp.

Source: me, I've lived on all continents

India is very much a WhatsApp country. You can even access government services on WhatsApp!.

Even Antarctica?

It's the one I've spent the least time at. Ok, that one I didn't live on, but I did visit.

I didn't use WhatsApp there. I had to SMS / tweet with my satellite device.

US bases won't let you put your phone on WiFi typically, with a few exceptions I dare not name in case USAP is reading this.