SMS+Messages or SMS+Hangouts, Facebook Messenger, WhatsApp, Kik, WeChat, Viber, LINE, BBM, Telegram, Signal, Sicher, and I'm sure I'm missing some. Used to just install a multi-protocol chat client and be done with it, but now everything's a fancy service with special clients to sync state across devices and whatever else they do.

> and I'm sure I'm missing some

Skype?

Do people use it for messaging? I know it has it, but it's always seemed secondary to the voice/video.