I will discuss a few IM client by its protocol, platform, speed, security and privacy, especially in China, People’s Republic of.
Signal
The open-source end-to-end encrypted messenger was unfortunately blocked in China on Mar 21, 2021. I have used it for a period of time, and stopped when it’s blocked.
Session
I’ve just tried, no connection available, just like Tor, it hangs there forever.
DeltaChat
The app use email infrastructure as media in communication, however, few people in China use email now, many of Chinese only have qq mail like [email protected], and it’s expensive to enable SMTP and IMAP service in qq mail, which is required to add it in DeltaChat.
Wire
Haven’t used though, I heard it’s blocked in China years ago.
Of course not.
Of course not.
Line
Of course not for a proprietary software.
Briar
Its messages is delivered via WLAN, Bluetooth or Tor, and we don’t have many relay devices in China.
Tox
I have just tried, no connection available, years ago it’s usable though.
Telegram
The most friendly IM, it’d be perfect if it does’t require phone number, abandon the Premium project and TON.
Matrix
So many people recommend this, but it’s more centralized than anyone. The most popular server matrix.org is blocked years ago, and it’s very rare that someone self-hosted a server (I haven’t heard).
Discord
Blocked in China, and, proprietary, so no.
XMPP
The most recommended IM, there’s many servers and clients open-source, support end-to-end encryption, decentralized servers, hard to block.