I'd also recommend Telegram. Whether or not secret (end-to-end encrypted) chats are implemented is up to the client's author. Not having secret chats in Teleg

I'd also recommend Telegram. Whether or not secret (end-to-end encrypted) chats are implemented is up to the client's author. Not having secret chats in Telegram Desktop was a decision of the author - https://github.com/telegramdesktop/tdesktop/issues/5 https://github.com/telegramdesktop/tdesktop/issues/5 They work in cutegram (qt based client. OS X, Linux, Windows, OpenBSD, Arch AUR, etc) - http://aseman.co/en/products/cutegram/ http://aseman.co/en/products/cutegram/ They work in the pidgin plugin (which works on all of the platforms supported by Pidgin) - https://github.com/majn/telegram-purple#readme https://github.com/majn/telegram-purple#readme They also work in telegram CLI (which many bots are based on) - https://github.com/vysheng/tg https://github.com/vysheng/tg